#1 - Sept. 9, 2016, 6:23 p.m.
Acknowledged as a major issue, that it's not fun to spend so long ramping up on a mob and then have it die before you're finished. Tangentially, they're looking at a hotfix, maybe within the next week, to address the base shard count from 1 to 3.
More generally, he used demonology as an example of where they could make improvements - allowing the warlock to build up an army of demons and bring that group from mob to mob instead of having them expire so quickly, similar to a Diablo-style necromancer.
Limited Mobility & Too Many Hard Casts
Acknowledged as a concern, but not likely to change. Their design philosophy is that they should "double down on strengths" rather than "shore up weakness". The vision for warlocks is to be less mobile, more tanky, and they'll work on reinforcing that moving forward.
Destruction Mastery RNG
Acknowledged people are unhappy. The design intention is to be similar to crit - variance will average out over time. Acknowledged that it's not fun to get low numbers during a limited burst window (e.g. buffs aligning). No word of anything changing.
Feedback in General
Complained that it's hard to find the good feedback with all the petitions and spam. Said he has visited the warlock forum several times to try to find actionable feedback, and likes to be linked to consolidated issue posts that have been acknowledged as credible by the community (lots of upvotes, maybe) with good discussion.
Yes, that's all
Nothing about artifacts, visuals, glyphs, or low DPS in general. Demonic Empowerment was only tangentially addressed by the "ramp up" issue (he did mention the spell, but not that it's hated).