It's not so much I have a problem with using different digital distribution services for different games. I'll happily use Steam, Origin and Battle.net, but only because those services work well.
I've been unfortunate enough to use Uplay twice before (From Dust and Watchdogs) and both times it was a less then stellar performance on their part. Buggy, slow, unpredictable. If they can iron out the kinks though I'll be happy to use it too.
Everyone always forgets what a shit show Steam was to begin with.