I used to play TF2 a lot back in the day but yes, I think they have gone a bit too far with it. I was fine with the weapon updates, I really looked forward to a new class update along with a new 'Meet the ____' video, but there are a lot of things that have since turned me off it and now I haven't played tf2 in about a year.
Firstly, the more recent development of adding new items if you pre-order certain games just comes across as really gimmicky. To a lesser extend the new micro-transactions thing annoys me too. Maybe it's just me, but I believe that once I've paid for a game I shouldn't have to pay for it any more, it's for this reason I hate Battlefield Heroes. However with BF:H it's more to do with the marketing of it being 'free to play', when that's literally bloody it. You get the basic game, but if you want anything resembling a decent looking character or adequate firepower out comes your wallet and EA's vaselined-rubber glove. Also to clarify, this doesn't include singleplayer DLC, I don't mind paying for a few more well-constructed hours of gameplay. I can agree with the sentiment of wanting to pay amateur content-makers for their work, but surely if you're a fan of the game you're making content because you enjoy it, not to look for a profit.
However, more OT, the main reason I don't like TF2 anymore. It may seem like something fairly trivial but the 'hats' system put me off the game completely. Original TF2 had a really, really nice visual aesthetic, but the inclusion of stupid looking headwear ruined the feel of the game for me.