currently, there is very little reason to build skeletons, especially past the early game.
I often will consider the skeleton-test when judging a strategy game - how many skeletons does this game let me throw at my opponents? So far, Dominions 6 is the winner. I digress ~
If skeletons share damage with nearby skeletons while above ~20% health, they will better be able to utilize their regeneration mechanic, which currently feels very low impact.