Sure, Tommy's story isn't exactly credible or original. I'd even go far as to say Tommy's not a great protagonist. He's a traitor to the family and bosses people around to get what he wants, though redeeming himself with occasional considerate and human behavior (unlike Trevor).
What? hell no, if anything, Trevor was a considerable improvement over the whole 'bossing around because this town is full of idiots' Tommy. Whereas Tommy Vercetti would only occasionally show signs of 'human behavior', Trevor flies through it from beginning to end.
You might not like how Trevor decided to went nuts in one scene and stay cool in another without much reasons as to why the opposite didn't occur for example, but at least the signs of Trevor's own subjective thoughts are there throughout the game.
It just bolts down to a question of whether you look past at how 'disgusting' it is or not, of whether you consider his actions to be an equivalent of the equally mad setting and universe the games takes place in or not.
If anything, Trevor is also a living fourth-wall-breaker of the series.
The fact that his voice and mannerism reminds of Crypto from the Destroy All Humans franchise, which is in turn based of a loose Jack Nicholson, you've got one big blender of satire entertainment, while still staying true to 'his' temperament mood and character.
It is considerably easier to visualize both Trevor's actions and the environment he is placed in as a whole, than Tommy was in relation to the Vice City story or sandbox.
Back on topic.
Personally what currently bothers me is Franklin, or rather, the fact that how supposedly everything is to revolve around him, and yet at the same time, spend so much less time -or even significant time- with him than it is done with Michael or Trevor.
Franklin is introduced as our first and only playable character in the early hours of the game, and we kind of grow to sympathize with him. It was meant to be so. Franklin never does or says anything particularly troubling, and the decisions he takes -or lack thereof- is played in relatively 'safe grounds'.
In-game, his special ability to slow traffic time is considerably helpful to first-time players, so that they can adjust to the game's driving mechanic more easily.
By the time all three characters are unlocked and switchable however, you would have gone perfectly at ease with the game's driving mechanics and only resorts to use Franklin's ability only during extreme situations, and if the game lets you play as him.
It doesn't help that the character's individual stats doesn't stay the same throughout the game, meaning that each would have its strength and weaknesses and you will have to deal with it, or at least make it a lot less easier to max out all the character's stats so easily by plain natural progression.
But you only start to notice Franklin's weakness by design once you unlocked Michael and subsequently Trevor.
When Michael becomes a playable character, you are added with new side mission activities, new phone contacts and hang out partners. These are the key elements in prolonging the game's length time besides the main story. And same occurs with Trevor. Although Trevor lacks in phone contacts and hang-out partners, his inclusion leads to even more side missions, some only exclusive to him, and the game introduces the majority of the weapon arsenal through his character as well.
Franklin therefor is left with almost nothing 'exclusive' to him at all as the game progresses.
Considering the short amount of dialogues recorded for hang out partners, you would have probably made through all the uses in hanging out with Franklin's set of friends, and after Trevor, no new partners become available exclusively 'for' him.
Side missions can be tackled with just about any characters, so you will spend all your time with Michael and Trevor and not finding enough reasons to play with Franklin.
And his slow down traffic special ability loses its uses once the player gets used to handling the driving mechanics, whereas Trevor's rage and Michael's bullet time can always have its uses, notably thanks to the game's design of making our characters weaker, and therefor the combat-centric abilities of the other two are more needed.
Franklin does have four unique properties that only he can purchase, more than the other characters. Unfortunately properties in the game only rarely earns you more missions, or significant missions at that.
Franklin can mod his vehicles for free, which is nice, but if you play your money right you don't need to treat it so carefully and considerate by the time you have enough to buy properties anyway.
Franklin can also have free cab services, why not, but was that really a notable boon to us?
Franklin's roles within the game's switch mechanics in story missions and heists are also kept low and have less impact than the roles carried out by Trevor or Michael. And if all three characters are available during a shootout, why bother engage with Franklin, the only one who doesn't have combat-centric special abilities?
But all of this complaint wouldn't have reached so high had it not been for the fact that the game's story wishes to have it centered around Franklin nonetheless.
The most obvious element being the choices of the various endings. All three centers around how Franklin wishes to deal with the situation. It is his choice that will have the greatest impact.
Why is the character that has the least amount of impact on gameplay and story being asked to deliver the final note? Why does his words matter and not the others?
Yes there were suggestions, with the conversations he has with Devin especially, that lingers about for the second half of the game. But other than those few words, Franklin is pretty much just the fellow there for the ride. He repeatedly insists on wishing to continue to aid Michael not because his character development asks for it, but because he is an obligatory 'third character' sake of this three protagonist game design.
It explains why the only Strangers and Freaks missions that counts towards the official 100% completion are the ones that can only be handled by Franklin, regardless of how easy or hard it is compared to the other missions for Michael or Trevor. Because Franklin is the only one who can not die, the choice for that possibility is completely unavailable, and therefor his side missions never becomes 'miss-able', and won't impede on player's completion.
It is also why side missions only made exclusive to Trevor are not accounted for in the Pastimes and Hobbies statistics, since he isn't necessarily deemed obligatory to survive the game.
The sole significant impact Franklin can lead to the other protagonist is through Lester's assassination assignments, which leads to the biggest money earner in the game. But if the player isn't aware of this 'exploit', or didn't wanted or felt the need to earn huge sums of money in the first place. Then again Franklin's role is diminished.
When it was confirmed that GTA V would have three protagonists, it seemed obvious that Franklin was going to be my least favorite, mostly because the way the game marketed his character was a string of things that we've already experienced before in past GTAs, compared to Michael and Trevor who brought their own new flavor to the series.
When I started playing GTA V I was relieved to see Franklin's character taking a route that wasn't the one I dreaded for, but then disappointed that his presence pretty much vanishes in the second half and suddenly made the foreground character for the endings.
As a side note, at times it also seems a bit forced as to why Stranger and Freaks characters would only interact with one specific protagonists, with only just a couple of exceptions.
Maybe to force players to engage with all three protagonists? would have been more daring if they allowed players to choose which protagonists they wish to use to engage with which NPC.
Risky, as the player may just stick with one character throughout the whole game and miss out content made for the others, but daring.
And greater replay incentive for that matter.