The biggest alt-unfriendly thing about Legion so far is the fact we have to do some things before we "start playing" when we reach level 110, things that sometimes take very long, like:
-order hall campaign to unlock 3rd relic slot
-legionfall questline to unlock traits 2.0
I understand the RP value of the questlines, and would want them to remain available in case players want to do them, but I stongly see the fact we have to grind all these things just so we can start actually playing our alts can be an unnecessary pain in the ass