I have to assume Quake's lack of weapon switch animations was more due to a lack of polish than anything else (since every id Software shooter before and after it has them) but there's a little freak goblin somewhere in my brain who loves being able to do a little finger dance to rapidly mix up my barrage on the fly.
A fiend rounds the corner and I can just go 'grenade grenade super-shotgun single-shotgun super-shotgun single-shotgun hee hoo get deleted idiot' over the course of like, five seconds. It's not a feeling I can get from many FPSes, even from this era.
