A +2 AC for a feat is a pretty good deal. Paragon armor specialization feats only give you a +1 and have non-trivial preqs. For an heroic feat it's almost a no-brainer.
It's funny, because in 3e, there was a big silly debate about putting armor enchantments on bracers or clothing instead of armor. In 4e, they not only put in Cloth 'Armor' that was outright just clothing or a robe or whatever, but they also made it a moot point by giving Leather proficiency no preqs at all.
A low STR preq, like 11 or something, would make it more of a decision for the wizard. STR is immenently dumpable for the wizard, while DEX (wand mastery, initiative) and CHA (Spell Focus) have thier uses. So, going for leather would mean declining to dump an 8 in any stat, and thus, maybe, having one of your more important stats 1 point lower. A CON preq would be meaningless, even a non-staff-mastering Wizard doesn't want to dump CON.