Well, they're committed to provide as secure device as possible. There's no love for Google in the team.
They recommend Google play over fdroid due to some security concerns, not because they like the service. The reasoning is available on their discussion forum.
And yeah, it won't officially be supported on other devices than the upcoming Motorola and perhaps the next pixel. Too bad.
It's the only news I've heard about new-phone-tech that's gotten me remotely excited in a long time. I'm too poor to be buying new devices though so I'll have to let others do the beta testing for a couple years.
Not my preference, but they seem so far ahead of other ROMs right now that I use it still.
I do believe people have built and installed it on other devices without too much trouble, but I don't think that'll ever be supported.