Because the flashlight must be compatible with 65mm to 70mm batteries, if you use 65mm batteries. It will be significantly shorter, and now I provide the corresponding accessories.
This requires customized drivers. For example, turbo mode needs to be turned on by double-clicking the switch, and the working time will not exceed 30 seconds.
Heat can be managed in a couple ways. Either by amp limiting in the driver design (permanent), or a driver design that gives you the best of both worlds:
support max amps via a direct FET channel, or amp limited depending on the emitter used (ex: linear regulated)
smart thermal management, as implemented in Anduril or Anduril 2
It may require high quality springs, or double springs, or bypasses.
This is why a few of us have been mentioning an Anduril or Anduril 2 option because you can get the best amps a LED supports, but with the safety of true thermal regulation/management by limiting the max temperature via an MCU internal sensor, or external sensor.
I would like to see more aggressive thermal fins on some lights as well. For example with the new 3X21A, there are many fins in the proper area but they are too shallow - they need to go deeper into the body, and if they did, it should reduce the weight as well -- another advantage.
Less aluminum mass if possible, more surface area -- good goals.