IV is not much of a crowd pleaser, which is fine. V was designed to be as broadly acceptable and marketable as possible, both to recapture the lost audience who was disappointed by IV and to create a bedrock for Online. IV, while following then-current industry trends as well, was more of an artistic effort first. Rockstar obviously build and marketed the game to be a best seller, but the artistic vision took precedence. TLaD even more so. But from TBoGT onwards, Rockstar just decided to give the people what they want and their own creative expression suffered as a result.
Sorry for a bit of a tangent, that's something I'm very much worried in regards to RDR2 too. That instead of some new excercise, a foray into a new territory, like IV, TLaD, Redemption, LAN and even MP3 were at the time, all RDR2 will strive to be is to merely recapture that spark and magic of the first game, just like V wanted to mash together everything people loved about previous GTA titles. Given how strong of a game RDR was an how long it has been since it came out, it would still make for a decent game, but I wish R* would again surprise us and challenge us like they did from 2008 to 2012, instead of just delivering wonders we all already expect.
Still, the critical reevaluation IV underwent in the last four years is something that should not be overlooked. The internet is much kinder to IV than it was nine years ago, partly from V lifting the burden of being the "big, current GTA" from IV and allowing people to look at the game for what it really is, unbound by expectation and partly from, I'm just going to say it, the younger people who played and loved IV in their teenage years having more of a presence in the community and the critical circles, while being able to articulate and frame their arguments better and more efficiently.
For what it's worth IV tends to be respected and appreciated way more these days. It's definitely not just here.