Careful what you wish for. Lots of aff locks wished for a minimum "resource" (= no. of souls) at the start and now ended up with that minimum equal to maximum of 0
If you wish that same for demo, you might just run into the next PTR note of "all existing demons of Demonology warlocks will disappear at the start of an encounter. So will the artifact buff from dying/expiring imps."
However: I do agree with Blizzard that it is MUCH easier to balance when every fight starts with 0. This way, they can still make reap somewhat meaningful, despite the fact that with the new trait and the leggy cloak, you could theoretically have 100% uptime.