I left out talking about control. Everybody knows using a controller sux for a FPS'er.
I believe using CTRL for ducking is very weak. So I think a player using right click = jump and spacebar as ducking can pull off the duckjump much easier.
Seems to me like more and more games are taking away your ability to attack when moving. "Sprinting" makes it so you cannot shoot. I'll have to admit that it looks cool to me, but I've never played a game with the feature.
Then take Dark Messiah for example. When you jumped/landed, etc your attack would reset. Also note worthy is bob effects. When you landed you would get this crazy bob.
Games are also using "stamina" more and more. Once that runs out you feel you're moving as slow as a console FPS. They're now even including it in your attacks.
Games also use "weight". Sometimes it's just based on your weapon or armor type. Others using how much crap you got in your backpack. I feel that weight for backpack is just horribad. If anything, if you go past a certain weight just stop movement or slow it down by %50. However, if you got tiers of weight I think that just takes away from gameplay.