Honestly in my opinion it is an awful idea, ruining the whole aspect of creating your own moves, yeah it could work for one or two mods like boxing or wrestling mods but all of three people play those mods outside of sp on a daily basis anyway. Maybe making it optional or an in-game command would be a better idea such as real time ghost, because I'm pretty confident that most of the community wouldn't agree that this is a good idea depending on how it is implemented into the game.
But it also could be a good idea. could bring more players into the mod making community. Imagine starting out a parkour mod hanging off the side of a cliff or from a rope or building(if not possible already) depending on how it is used it could be a fun new feature.
relating back to how it should be implemented, the only way people would most likely accept this feature is an in-game command that turns it on. because I for one don't want to join every single server and have to use a stance created by someone else I'd rather use my own.
So really, just depends on how it is implemented, so the idea isn't all that bad unless of course pay-to-win(Well said Rfifan), In my opinion.