I wouldn't say she *needs* Dex, but a negative modifier is frustrating - especially when it would be so easy to fix. Wouldn't you agree that a PC who is both restricted to Medium Armor and tends toward the front line probably shouldn't have a build that gives her a permanent AC debuff?
If you don't want the negative in her Dex, just put points into it at level 4. Or have people forgotten that?
Z.