The thing that gets me about bluetooth is how nonsensical the conflict resolution is. Like, if I'm playing something through a bluetooth speaker, and my wife wanders into range while listening to a podcast on her phone, it will automatically connect to the speaker and boot me off. How does it make sense to auto-connect when another device is already using the speaker? Similarly, I'll be listening to my bluetooth headphones, and my wife starts her car in the garage below me—suddenly my phone disconnects from the headphones and connects to the car instead. If I'm already playing through one bluetooth device, I probably don't want to automatically switch to a different one - especially one with a far weaker signal/likely farther away.
I get that these aren't trivial problems to solve, but they certainly seem possible to improve on, given the maturity of bluetooth at this point. Also perhaps they aren't the fault of the protocol at all, but just the choices made in programming phone OS's. Regardless, it's annoying!