Of course, from the perspective of a Bittorrent client author it's much easier to implement TCP-over-UDP than to depend upon raw socket support / install a custom congestion control algorithm into the OSes TCP stack.
If there was a generic utpclient/utpserver pair of applications that I could use to proxy non-uTP applications, as there is with CCP, I'd try using uTP/LEDBAT. But to my knowledge, there isn't.
Of course, from the perspective of a Bittorrent client author it's much easier to implement TCP-over-UDP than to depend upon raw socket support / install a custom congestion control algorithm into the OSes TCP stack.