Spy in the blue base!

[Xiahou]

Valve dislikes the grenades themselves. If you have ever played TFC, you surely must have seen the constant grenade spam that caused everyone to die constantly, without ever accomplishing anything.

Besides, if they gave classes grenades, then the Demoman wouldn't have any purpose left to him.

I played TFC pretty extensively and I can't say I remember grenades being that big a problem. Each player was limited to a very small number so while they were used heavily, it's not as though a player could just sit there and spam them all day long.... for that, you need to be a demo.
Grenades were really only a secondary point anyhow- I can live without em.

I just don't care for the constant meddling with the gameplay mechanics that all of these unlocks cause. They should've kept things simple- each class should be good at once specialty and have the weapons it needs to do it. I really don't care for the willy-nilly sprinkling around of unlockable weapons.

I really liked TF2 when it first came out, but I've been pretty well turned off of it since then.