Some Questions

[Eruantien]

As far as optimal gear goes, that's actually not quite right. Optimal level is only on older items, which are for the most part inferior to begin with, and cannot have materia attached either. The penalty for equipping items with an optimal level above yours is quite severe... and honestly, you shouldn't be equipping dated gear in the first place (Except for accessories, which are getting non-dated items in the next patch. Once the new items come out, you'll probably want to use them instead of the old). All of the newer items have Required levels instead, which means you absolutely must be that level or higher to use it.

Not true some new gear still has optimal level, woolen cowl is an example, raptorskin jerkin is another.

To the Question the hit for gear that is allowed to be equipped under the optimal level is quite severe, for example you do not get any of the bonus stats (str+ mnd+ etc) all you get is very harshly reduced def, mag def etc.