As a Roblox developer, it is currently too hard to replace custom body parts.
ReplaceBodyPartR15 currently only works with existing limbs.
I would love to make it work with custom bodyparts called “RightWing”, “LeftWing” or “Tail”.
I don’t want to do Humanoid:BuildRigFromAttachments() just for one part.
It seems inefficient.
I would also love to have less lines in the code 
If Roblox is able to adress this, it would save me some time with bodypart replacement.
I’ve also found that this function is very limiting and meant to post a thread on this topic before, but it always felt weird to only suggest the change here.
The way humanoids are currently feels like they are very geared towards Roblox’s default rig types (R6 and R15) and don’t offer much support for custom rigs. This, on top of many other issues, makes me believe that while this function in particular may be worth replacing with a more flexible one, it’s not worth arguing this for a lot of the weirdly specific humanoid behavior. Humanoids in general need replacing, not just this function.
tl;dr I support this, but I really hope Roblox’s focus shifts away from updating the Humanoid class and onto making something new to replace it.
Yeah, I made a thread about SwimmingSpeed / ClimbingSpeed. We should have a bit more control.
A change like this would be more than welcome in my book. My upcoming game relies entirely on non-standard rigs that I’ve constructed myself, and player skins / alternate body features are a must for my character system.