Instead of having many conventional LEDs to make up a bright light, why not just make one LED where the actual diode part of it is very fat, long, or multi-stranded?

also instead of wasting 50% of the light because of refraction within the plastic, make the actual light emitting part like the filament of a regular bulb. don't touch it with anything, just surround it with a vacuum and a bulb.

instead of using phosphors to make pseudo-white light, have many leds (as above) of different colors which roughly add up to a natural spectrum