Maybe it's something you pine for more when you play a lot. At the moment I'm able to predict and extinguish almost any enemy because I know pretty much exactly what he's going to do.
For example if it's a Pyro I can always let him get close enough to hit his feet with a rocket, which'll launch him into the air so I can finish him with a mid-air or ground rocket. But if that Pyro could be carrying a shotgun that fires flaming rounds, suddenly my counting on him being fairly useless at medium/long range goes down the pan. It'd force me to rethink the same old approach I've routinely annihilated Pyros with for over six months. ![]()
It'd really mix up the strategy in a good way I think. TF2 is good and balanced, but it does get stale if you play it a lot. After a while you end up seeing and doing exactly the same things every time you play a certain map because there's not much else each class can do while remaining effective.