I honestly don't get the criticism.
The AC-games are hugely budgeted games. The cost of porting it is probably miniscule compared to what they make up for it in sales. The fact that we're now in a situation where we'll have cross-gen ports is not something that will be unique to Ubisoft. Nor is it a shameless money-grab.
They were definitely going to make AC:BF for PS3,x360, WiiU and PC anyway. Being one of a few established franchises among the launch-window titles for both the new consoles is obviously great opportunity.
As much as I love indie gaming, or first-party vanity projects/labours of love, I don't get the hatred for 3rd party developers doing what 3rd party developers by design will do.