I realize this is an old thread, but I just searched for a solution to this issue, today.
I too lost Moto voice commands on a RAZR M.
I tried uninstalling updates for Google play music, with no success.
I tried downloading the Moto voice commands app, but could not use it, with the "stock rom" I am using. It said something to the effect of illegal action.
So, I decided to embrace the Google now.
I found I had to actually turn on Google now.
Further down in the settings>voice > hot word recognition on
And >bluetooth audio on.
Then accounts & privacy >contact recognition on. This uses your address book to make voice calls.
It works just like the old Moto voice commands. :-D at least for BT phone calls while driving.