In order to have a unified universe, you have to have both licenses held by the same company in order to avoid conflicting story directions.
I, in general, like Angel the Series through IDW. I'm not slamming them at all. If they also had the Buffy license that would have been okay, too. But these two 'properties' are so inter-related that it just isn't practical to treat each of them as a totally separate entity. If anything, there should just be once license called "The Buffyverse" in order to avoid splintering continuity between them.
I really enjoyed Angel(us) vs. Frankenstein('s Monster) and Angel: Blood & Trenches, but as soon as dealing with the 'Aftermath' of Angel's ongoing title, it just didn't seem to make sense for two different titles to be writing the BTVS: S8 and Angel: S6 titles.
To tell the truth though, I kind of would rather have IDW take both titles over Dark Horse - I like the artwork and coloring a lot more. Both creative teams have left a lot to be desired in writing, so I think that's a draw....