There is such a thing called Turtlewax, aka JZ & Vans deep buffering system, rewritten specifically for IKEMEN GO. The zss version was rewritten by Jesuszilla and the lua version was more recently remade by kamekaze. Both are which are very good, and fix double press issues. Doing akuma's ashura senkuu has never felt easier!
The great part about this deep buffering system exclusively for IKEMEN GO, is that you can apply it simply very easily to any character. It no longer looks like a jumbled mess like it does in MUGEN.
[State -1, Hadouken]
type = ChangeState
value = 1000
triggerall = !AIlevelF
triggerall = Map(QCF)
triggerall = Map(a)||Map(b)||Map(c) || Map(r_a)|| Map(r_b)|| Map(r_c)
triggerAll = power >= 500 && var(20) <= 60
trigger1 = ctrl || StateNo = 40 || StateNo = 52 || (StateNo = [100,101])
trigger2 = var(6)
With how simple it is to implement these command buffers, you could take older works like Warusaki3's stuff or even other Japanese creators work and very easily implement the new a better command buffers, without needing to do the insane shitload amount of work you would have to do in MJGEN.
Also, if someone is using mostly stuff from Jmorphman/Karma C type of work, they already got explodsive buffer, so there's no need to use the default ikemen input system.
MUGEN is still more popular due to how long it has been around, and because many MUGEN users are usually content with the lack of online fight capabilities (not everyone can use parsec). IKEMEN GO on the other hand has a growing fighting player base which is good, due to how easy it is to get matchmaking done.