[PvK]

Yeah, some nations have better defense than others, and for some it is pretty good, for others not so good, and for all, better combined with real units.

I wouldn't say increasing it is really necessary, but it could be an interesting variant. Just keep the relative existing balance between nations in mind, and don't try to make all nations' defenses the exact same value as each other, since no doubt the unmodded defenses were chosen with care.

PvK