Bluetooth won't work after 7.2.1 update on iPad or iPhone

No, you can't remove the update. I doubt that your problem has anything to do with iOS 7.1.2 since Bluetooth is working fine with iOS 7.1.2 on both my iPad and iPhone.

I have a similar issue. I updated to 7.1.2 last night. Now my Bluetooth audio doesn't work.

The iPhone appears to be paired with my Bluetooth enabled car stereo, but will not play any music.

Initially the stereo said 'Bluetooth connection failed' but then I disconnected and re-paired; now both the stereo and iPhone say 'connected' but still no audio.

If I press play on the phone or stereo, there's no response.

I can confirm that my Bluetooth keyboard pairs fine and I can type, change the brightness and volume but I cannot pause or play music.

My guess is that there was a change to the iOS Bluetooth Audio functionality. One that's introduced an incompatibility with one or several of the Bluetooth audio profiles: iOS: Supported Bluetooth profiles

Vid

To follow up;

I have a bit more anecdotal evidence that this issue is related specifically to an iOS 7.2.1 change to a code supporting a bluetooth audio profile.

Probably:

Advanced Audio Distribution Profile (A2DP)

and

Audio/Video Remote Control Profile (AVRCP 1.4)

Basically I tried my iPhone in another car that only supports Bluetooth spoken word (Hands-Free Profile?); like Siri, directions, phone calls, etc... but no Music / high quality audio. It worked fine.

I did have to disconnect and re-pair the phone but after that it worked.

My issue is resolved. Last week my devices all connected successfully and audio control and playback was back.