Not all types of LED are so fragile. GaN LED show negligible decay even with heat-sink temperature at 105 degrees Celsius when compared to one whos heat-sink maintained 55 degrees Celsius. Yes, I know that this is just a recent research paper and not something available right now, but your point regarding temperature dependence might be much less significant in the near future when compared to current state.If you drive them hard in a hot environment its significantly worse.
Eventually maybe but my point is that at the moment the tech isnt quite there and LEDs are complex, finicky and difficult to drive correctly. The article says match in the coefficient of thermal expansion It took forever to get decent 3W leds out there into the market at a resonable price. Even now 100lm/watt LEDs are pricey.It is very challenging to grow high quality GaN on Si substrates because of the huge mis-
so im guessing that means were a decade out before they are affordable.