It all started with the 80-100kg class of heavies. That was the TV show.
Feathers came forward due the ease of starting one.
Take cheap batterydrills, a decent RX/TX and some chopping/particle/mulitplex board and you have the makings of the basic featherweight.

For lightweights, you'll have to look at heavier duty batterytools, and those don't in the flavor "cheap" or even "affordable for drastic changes".
Starting a drivetrain from scratch isn't given to every starter, and even with the right knowledge and tools it never will be called cheap.

Otherwise you get into the realm of electric wheelchairs or mobility scooters, and those are more suited for middleweights and low power heavies.

In short, The historical popular classes became popular because there isn't any overlap in used parts except RX/TX.
Antweights, featherweights and heavies are so widely spread in weight that it is obvious why.

Any class added in between is just diluting the playing field.