I first saw this news tonight and kind of thought, "oh, of course the PC gets screwed again by nonsense delays!" But then I remembered just how much trouble I've had with new PC releases just in the past month:
16 crashes with Forza Horizon 3 in the first 5 hours after launch, Mafia III (just like in general, ugh), and a couple of crashes with Battlefield 1 last night. The moment I remembered any of that I thought that a delay is a great idea.
Take as much time as you need, Ubisoft. I'm tired of playing broken games on launch day.