Most elves are not Wizards. I bet there's more Elven Rangers than Elven Wizards. Also there's a lot of DEX-based Elven fighter/rogue/bard, or even STR-based high DEX Elven barb/fighter/pally/etc/etc. Don't even have to count sooo many Elven multiclassed builds out there other than wizards.
You're right though, High DEX doesn't mean anything to wizards now that we have the feat: Insightful Relfexes,
but high DEX still means something to sorcerers, for high Reflex save (=guarantied half damage from most spells).
Unless it's a raid quests,
High DEX WF Sorcerer = the Most Deadly, yet the Most Indesructable in the game. No one can match its "DPS + Survivability"
(Oh well, I'm talking about 14 starting DEX here, not 18 lol)