This is pretty standard operating procedure for blizzard, been that way for retail for a long time. Don’t address or fix combat related bugs until the content where they heavily impact (pvp for a lot of current things) becomes the main focus, which will be phase2/3 (phase 3 bgs being the main one).
Melee leeway, DRs, Vanish bugs, druid mana drain (and most other druid related issues) aren’t causing enough of an uproar in pve so they’ll ignore it until they cant.