The problem is RC4 is super efficient, especially for devices like Android phones which don't have AES-NI and run on battery (both for the CPU and the radio...)

The problem is RC4 is super efficient, especially for devices like Android phones which don't have AES-NI and run on battery (both for the CPU and the radio...). Deprecating RC4 in that environment has real cost for end users, as well as for the server operator.