Examples:
* High dex helps spin, so it is useful for spear using anti-paladins, or staff using druids.
* High dex helps evade.
* High dex helps hit people who use their high dex to dodge you. (Not just because it boosts your hitroll, but because attacker dex factors into the calculation.)
* High dex allows you to carry more, which can be useful. For example, more damage redux or more limited preps, curatives etc.
* Drow shaman can get dodge through the spider's grace edge. It'll give you the dodge skill with the percentage permanently equal to whatever your dex is. Now 24% may sound like bad dodging, but it is a noticeable boost.
* Conjurers with familiar agility edge get dodge skill equal to their dex when their familiar is in the room with them. That's useful if your familiar isn't too fragile.
* Dex helps you avoid fumbling when greased, so you are less likely to drop that potion when you really can't afford to.
* Dex helps you get out of bindings.
* Edited to add: High dex is very useful in lowbie pk if you adopt an ac-based defense.

I hope, without giving an exhaustive list, that I've demonstrated that dex IS still useful.