I have the original Moto X from 2013, which had been a pretty decent device. It too had been promised OS-level updates (not just patches) and it would go to Lollipop shortly after release. The final release is just getting rolled out now, just as the next version of Android is hitting devices. The delay was due to its custom X8 chipset and limited hands to get the job done. At least this time, Motorola is probably being upfront about it or still haven't assessed the viability of the upgrade. Oh yeah, and you still have to wait for the carriers to approve the specific updates.
I've given up and gone back to iOS and got the device unlocked.