I don't think it's that game breaking.
A +2 to Str gets you +1 to Attacks and Damages.
A +2 to Dex gets you a +1 to AC, Init, and Ref Saves.
A +2 to Con gets you a +1 to HPs, as well as a Fort save.
A +2 to Int gets you a +1 to DC, extra spell and Skill point, 1 lang.
A +2 to Wis gets you a +1 DC, Extra Spell and Will save.
A +2 to Cha gets you a +1 DC, and extra spell.
No, Str isn't very important to a wizard. Sort've like Cha isn't very important to a fighter. It's certainly Okay to deminish Mental stats for +1 to Fort and HPs (Dwarf) for a smack to Cha, or a +1 to Attack and Damage (Halforc) for a smack to Cha AND Int, but it's Not okay to get a +1 to DC, Spell, whatever, for a smack to a physical stat?
Let's not forget a mental stat for a mental stat. +2 Int/-2 Wis means you get the benefits, but then a hit to all your Wis skills, not to mention your Will save. A -2 to Int is a hit to your languages, and skillpoints. And Cha... Well, that's the dump stat.
Air Genasi I believe have a -2 Cha. However, Cansin (Chaotic Planetouched) have a +2 Cha and Int.