The concept of waste heat being beneficial is a red herring for a large part.  A 60W bulb generates 3.3 BTU of heat per watt or ~200 BTU total.  The best generators are 25% - 30% efficient so your 60 watt bulb requires 600 BTU worth of diesel fuel to power.  A 60 watt equivalent LED uses 10 watts/33 BTU total so requires ~100 Diesel BTU's to generate.  A decent diesel stove is 80+% efficient making it the heat source of choice.  Moreover, LED's by dint of less demand allow a smaller generating capacity or allow for an entire engine to be shut down if  the efficiencies in a community are scaled.  They also have proportionally less line loss from generator to bulb, aka distribution loss.  We were able to downsize a cabin from a 2kw Honda to a 1kw unit by converting first to CFL's then LED's with the bonus of being able to run an electric coffee pot with a few lights!