Some may not want to use OMEMO so it would be good to have option to disable it:
remove option to start encrypted connection
(somehow) prevent other party from sending us encrypted messages (@andrzej.wojcik - you suggested automatic replying with "Don't send encrypted messages" but maybe we could either remove our keys or influence OMEMOv2 to handle this usecase?)
Some may not want to use OMEMO so it would be good to have option to disable it: