It may just be me... but I'm sick of seeing great games get ruined by large commercialization and the fact that all of the companies that make them are money hungry! It seems if a game comes out and it's an amazing hit, the company that made that game will for sure ruin it a sequal that simply puts the name to shame!
Here's a couple examples of what I mean:
Counter-Strike (a Half-Life mod), started out as an amazing hit created by some canadians with time on their hands. It was such a hit that Valve purchased the mod so that they could package and distribute it for their own profit. Not a bad idea at first. It brought the game to a lot of people that may not have ever heard of it otherwise. In fact, the company worked good with the game for a while, they regularly patched the game fixing bugs and fine-tuning the engine. They even adjusted the way each weapons recoil reacted after each patch, which added to replay value for long-term players as well as evening the playing field for newbies. However, when they made Counter-Strike: Source, everything changed. There was no more dynamic to the game-play. You could no longer master how your favorite weapon would fire, and therefore no matter how much you played it you were still just as good as the kid that just installed it...
Another prime example is Modern Warfare. Now, I wont go into as much detail with this one since i've already said how i feel about it.. but basically you have a game that was way more of a hit than anybody could have guessed. I mean come on, they did it right, decent balance of weapons, the idea of "perks", "kill streak rewards" and a variety of game modes to fit different people, or just the mood you're in that day! MW2 just got a little crazy.. Mainly with their crazy perks and kill streak rewards.. I can find some form of realism in almost every perk from MW.. however in MW2... well, you may try to fight it, but you will ALWAYS recieve fall damage.. and a tactical nuke that simply ends the game?! Lack of dedicated servers for me means a lot because i like playing on servers with tactical rules of engagement, which simply isn't an option anymore.
I could probably come up with more examples (L4D/L4D2), but maybe later...