A way of killing the hot end fan was a long time coming.  For some reason, the MOSFET fan got a software controlled GPIO while the hot end fan was permanently powered.  The MOSFET fan could be controlled by a thermister & comparator but the hot end fan needs the gcode.  Helas, there probably wasn't enough memory in the 8 bit micro for fan firmware.

The key need was a way to use the bed as a space heater & filament drier without sucking dust into the hot end.   Other benefits were speeding up the heating, preventing hot starts.