Besides the reasons already given for RF, in power electronics, the Ron of
a BJT is far lower than a MOSFET. There is a melding of the two
technologies, called the IGBT (Insulated Gate Bipolar Transistor), but
they are only good up to a few dozens of KHz where true power bipolars can
switch ealily into the tens of MHz.

For audio and instrument applications where noise levels need to be below
2nV/Hz, MOSFETS can't even go there (without being dunked in cryogenic
fluid).

--
Gregg
*It's probably useful, even if it can't be SPICE'd*
http://geek.scorpiorising.ca