With more inhibition comes more control, which could increase focus at the expense of creative insight.

Speculative, or do you have any sources on that? It could be vice versa: consider e.g. the basal ganglia, with e.g. the striatum inhibiting the globus pallidus, which in turn inhibits e.g. the nucleus subthalamicus. The net effect of relatively more GABA in such a network (inhibiting the inhibition) is a priori unclear (it could go either way, depending on the relative weights of the two sequentially networked inhibitory structures).

While the overall effect is probably inhibitory (hence the usage for epilepsy), not all circuits are created equal in terms of facilitating creative insights, nor does increased overall activity necessarily translate to increased creativity. Note that stimulants such as methylphenidate can be used to treat ADHD, of all things.