I tell you what's missing from V's story.
Mission strands. In every GTA you meet a guy, work for him and that is an entire storyline (subplot). In V, there is very little of that - the stories connected to the "side" missions are very shallow and quick.
In IV, you got involved in jamacian gang war, russian mob, italian mob, shady government agencies - all this interweaved with but alongside the main plot of finding Florian/Darko and the eventual Dimitri story.
In V, heists are the focus - which is a nice fresh take, though not well done imo. Take away these heists and you're left with barebones of stories. Franklin and Lemar in literally a few missions. Michael and his dysfunctional family (the only story arc i felt was even remotely padded out), Trevor and his bullying of his "friends". The FIB/IAA story line was close to the ULPC one in iv - but remember that was just ONE of many in IV (or use SA's toreno storyline - it was just one of many).
I feel they comprimised about ten missions PER heist - meaning if there were no heists in V, we could have had about 60 extra missions. Perhaps that's an exaggeration, but that's what V lacks storyline - GTA has always appealed to me because of that. There are a million stories in GTA cities, and we usually saw a lot of them.
think about it - III, VC, SA, IV, LCS, VCS - you always worked for different people and did different things. Yes, many missions were similar (many "drive here, shoot him" - but that is the nature of GTA - if you have issue with that format, go and play a different type of game; it's like me complaining that Gran Turismo is "Drive here before X does" - that's what the game is), and there were many "slow" missions (which were very important in creating story and tension dynamics).
It was a great way of exploring and discovering the world. New characters, different storylines, all rolled into one. V stripped that right back, and the story really felt underdeveloped. They slapping this and that in, previous IV characters, shock tactics, added sh*t to make us think the story's bigger - yes, some missions were bigger and longer, but the story was shorter.
I see the RDR example, and that's a fair and valid point. But, where RDR had a lot of "ranching" missions, you have to realize that was what the game was - the Old West was heavily built on farming and ranching - that's what their economy was. There was no internet or stock market. Only cattle market and cattle drives. So those missions were simply part of the setting.
They also tied into the narrative. It was Marston's battle, his dream, to be a rancher.
RDR could have been longer, and indeed, i would have liked that, but in many ways it didn't need to be. It had a lot in it, and the setting was such that the pace was slower, if you allowed it.
As i said before, V simply did not hit the spot. It's a great game and I enjoy it, but it does not satisfy me as much as other games have done, but it's a hell of a lot better than most.