Somewhat to their defense - not really, but still - knowing what bones a biped will need for a game is akeen to having knoledge of the future.
During development you always tweak/modify improve your rig and character
So much so that you often start with plastic low poly stuff and end up with a better version of whatever top end cinematic actor you may be working with (idk, say for inatance cyberpunk’s jonny).
Its essentially not possible to make an asset that will work for everyone how they like it to work - no matter who you try and please, you always f* someone over.
In the metahuman case however, they are doing more damage to the indy community by doing even less…
Making game ready characters wouldn’t be a solution, it would mean further deterioration of knowledge.
What they should do, if they had any interest what so ever in this and the indy community - which mind you, they do not - would be to hire professionals and set up tutorials and pipelines on how to create custom characters for the engine properly.
Meaning with hair cards and phat assets and proper animation bluperints without code… etc.
So in short, my thing is never going to happen as they really don’t seem to care a single iota.
(The shoulder on ue4’s mannequin is still broken in all animations, since inception, for instance).
Your thing - creating game ready characters - is really only going to make things worse in the long run…