As the last poster said its Google holding them back artificially
I don't think that is the case. Its more like Google isn't helping them, and the path Moto was on before Google bought them sucked.
HTC showed this year that if you make a good phone out of fancy materials and you don't lock it down people will notice.
Imagine a Moto phone, 1080p screen, made of Kevlar, with a Maxx battery, no bootloader, and either stock android or a Nexus version. We would all go nuts over that.
One thing I love about the mobile community and news is that we are so focused on hackability. If you lock your bootloaders, or be a pain to work with, the community finds out and persecutes you for it
far beyond what is reasonable for the offense.
I mean, to most consumers locked bootloaders don't matter, but the Android press goes nuts over it and things like the "Google S4." Heck, Google themselves spent like 2 minutes on the Google S4 in their presentation but we all acted like it was the biggest news of the night.
Moto just doesn't get that when you lock stuff down you 1: Push away those who would be the biggest advocates of your product 2: Put negative "news" stories on Google that regular people don't understand but will change their opinion.