There are now a few games for which a "variant" system would make sense.
One example would be multiple swatches for Sims, or different variants of resource packs for Minecraft. (e.g.: https://www.curseforge.com/minecraft/texture-packs/undertale-soul-healthbar-undertale-death-animation)

I think it would be useful to have some kind of variant system, where you can upload multiple files under one version, but can also provide a variant name. Having the website & launcher ask you for which variant you want when downloading/installing.

The way it's handled right now, theoretically each variant, even if it's just minor differences, would need a separate project, otherwise most variants will be ignored.