I suppose in that particular case it does make you more than a bit weaker - no vampires and no Karas or Behemoths. But then, unrestricted leaders
is unsupported for some very good reasons (keeping the civs more or less balanced becomes a nightmare when you can use any civ's leaders anywhere, and even if balance hasn't been a top priority lately, there's also a lot of python scripts and other mechanics that assume that the leader will only ever lead their own civ, or civs in the case of multi-civ leaders) and if anything, it'll get even less support in future - Valkrionn has talked about removing that option altogether.
That said, we will be updating all the civs for 1.4, so I might make some changes to how the Mekara work. But even if I do, it's not very likely that I'll change the restricted units for Jamal and Zaria - they're sort of meant to represent different factions within the civ, and I like them that way, quite frankly.