Plane Sailing
Astral Admin - Mwahahaha!
True, it's easy enough to create a buffed & debuffed (normal) character sheet. However, if you're at higher level and half the buffs are dispelled and half are not, then it's not so easy. Or, if you walk into a beholder's anti-magic ray and not only are your buffs gone, but all the plusses from the various magic items you have are gone as well (at least temporarily.)
Certainly true, although unless a dungeon is about a horde of beholders or lots of creatures with added caster class levels it probably doesn't come up in the majority of cases.
However, the fact that it could come up at all was definitely one of the big failings of 3e in my mind (and I've said that since the very earliest days too. Cascading bonuses seems elegant but has serious practical problems!)
Cheers