- An engine produces 100 power / second.
- Gauss requires 50 to 60 power to fire.
- PPC requires 40 to 50 power to fire.
- Every weapon of course requires power to be fired.
- Result is you cannot fire anything but a gauss at any moment, or maybe no more than one gauss and one ppc at the same time. Cannot fire more than 2 ppc at the same time. Etc etc.
This suggested mechanic would allow the devs to FULLY control exactly which weapons could and could not fire at the same, as well as the number of a weapon type that could be fired at the same time. Medium lasers might use 15 power. So no more than 6 can fire in an alpha. Let the devs crunch the numbers till they get the combos they want.
Another benefit is you can remove ghost heat. Its no longer needed.
As homelessbill pointed out, yes its another mechanic, BUT it should better than the current bunch of junk mechanics we have to work with now.
Also power is present in the current gauss rifle firing. If you notice the lights in your cockpit dim when you fire a gauss rifle. At least in the atlas

Also power is present in the books / lore. When the clans invide the clan gauss rifle was introduced and when the pilots fired it, the mech would almost shut down. You could not fire any other weapons for a few seconds after firing the gauss, because its power draw was so huge.