Fair enough, although I'm not sure "half" isn't a bit of an exaggeration. Most of the spells aren't like that. Although, I will agree that there are just too damn many spells. It's one area I would rather see a HUGE paring down. Go back to Expert D&D where you had about 8 spells per level. Done. Not going to happen, but, one can dream.
It's really actually quite annoying that the caster turns often take twice as long as anyone else's, not because they're so much more difficult to run or anything, but, because so many times, the player drops a new spell, and often aren't 100% up on the rules, or, my personal favorite, "I cast ((Insert Spell Name)" Okay, sure. What does that do? "It does this and this and this" Uhh, ok. Do you have that keyed in as a macro or do you have the spell handy to show me? "Oh, no, it's in this book... oh, you don't have that book... well, that's how it works..."
DM bangs head on desk repeatedly
Look, if you're a caster, and you've just got that brand new polymorph spell, or animate objects, or whatever, take the thirty seconds to prep it to use at the table BEFORE you use it at the table.... Pretty Please.