Return of Reckoning

Why we don't use Kraz-a-Karak/Eight Peaks?
- we be got 2 sets of capital cities but still 2nd ones r almost empty...
- r there any problems to make KaK/EP capitals after successful city sieges? (for example: Destruction makes Altdorf 0 stars, so until the next city siege the capital will be KaK).

Cause at least the greenskin city makes any mentally healthy person to want to do /wrists trying to get anywhere. In all the times I been there to do regen pocket quest etc, I never even tried to actually walk out, just booked to manage to get out of there.