You can turn that back on in options, I think it's the last tab. It's to help frame-rate drop from too many 2D objects(the name text and health bars) on screen when there's a lot of pets and mines around.
I actually looked under the last tab (HUD) but didn't see anything there that seemed to fit pets. If you get a chance, please look again and let me know which one it is.
Whenever I release mines (or fire that Transphasic Breen spread torpedo) the unit names/labels are no longer visible after the initial launch.
Whenever dropping mines in a fire-fight, I'm not sure if they're still there, or have been wiped out in some other 'splosion. Constantly having to look behind me, to see if they're still there, and have landed on an enemy.