Removing the cooldown on AA does a number of things:
Firstly, it retains its buff style, something I personally thought was pretty important considering the origins of the spec
Secondly, it actually makes tuning somewhat more straightforward. The problem having been that archangel was 'necessary' to put us on par with the other healers, but outside of it we felt useless. This easily solves that issue, and adds a bit more "rotational" depth.
Thirdly, it addresses the heavily voiced problem of archangel requiring no real decision making, but instead of it being about WHEN to use it (which would always be a problematic focus for the desired kind of decision making), its now about HOW MUCH to use it, how much you want to stack it, can you afford to get a full 5 stack buff or will you be better off only using 3 stacks etc.
Fourthly, it actually does also manage to mostly address the issue of the baked-in inner focus. This is especially important for the early tiers, where the inner focus crit effect is much more desirable than the throughput increase, but will allow the playstyle to shift as our gear improves with later tiers when the throughput increase becomes relatively more potent. I think it's actually this final point that gives the most depth to the 'new' AA, because without this baked-in inner focus, there would be much less weight around whether its best to use it at low stacks or high stacks.
I'm genuinely impressed with this change (assuming it's intended), but I do wonder how much they actually thought it out, and how much it was just a random idea to try without any real logic behind it. It kinda feels like the classic 'disc hotfix', only they actually managed to do it during the beta this time.
If smite/atonement gets a little more tuning, we could be in a very good place me thinks
We shall see.