No, that's not it at all. People gave R2 heat because of how it changed from R1 -- many thought that it wasn't broke and didn't need fixing. C'mon, you know this, this discussion has been rehashed endlessly.
No, it needed to be fixed. Prior to the forced bundles that SCEE and SCEJ put together, RFOM was not a successful franchise, not nearly as successful as Insomniacs past products (Ratchet and Clank, Spyro, etc). This is especially jarring when you consider the folks that bought the PS3 at launch were LOOKING for games like this.
It had elements from shooters from 1999. Weapon spawns? Check. Walking Tank? Check. Run and gun? Check.
Basically, it was everything that no one was really looking for at the time (talking purely multiplayer here). This is an industry where you have to adapt and change to remain successful. It is a drastic change, but I can promise you the franchise is significantly more accessible to the end user now, and will do better on it's own, compared to the first Resistance title (excluding bundle sales).
For me, it IS people picking and chosing what they do and don't like. To say you hate a 2 weapon system, and then say you love x game? To say you hate slow gameplay, but then praise y game? Or even talk about the objective based gameplay, but then love a game that presents one objective for each gameplay type, etc...it's just crazy to me.
I've come to the conclusion that at this point, it's more about the graphics than it is anything else. Because the game still plays a great deal like Resistance, it's more balanced, and the maps have MUCH better design. I just see improvements all over the board...and they're still getting hammered by "hardcore" fans.