It's not the most uncommon thing to see figures in certain toy lines get various number of color variants or colorways. Some companies use it to expand the collectibility of the set as a whole, and some use variants as chase or super rare versions. It's done any number of ways, but today I'll share my thoughts on whether or not it's worth getting into.
Of course every collector is different, so you'll find a vast array of viewpoints, even when it pertains to one toy line to another. I think that's exactly it for me, some toy lines have certain keshi I want every variant of and some I'm OK with just having one. I think a couple factors decide that.
The first, for me, may be artistic quality or aesthetic appeal. If I just love the figure and how it looks and feels, I'll want more. At this time, to justify an uncontrollable collection, I try to keep my main collection without duplicates, but variants are accepted. This allows me to extend my affection for a particular figure.
The second would be rarity. I wouldn't necessarily call myself someone who chases after all rarest figure variants, but if there is one that shares a cool feature that would separate it from rest, I might just go after it. Examples of this might be glow-in-the-dark, glitter, color changing, artist customs, and artist proofs. Also, rare figures hold their value a lot more than standards do. Getting a rare figure that's valuable for a steal is always fun and feels good to accomplish. However making it too rare or too valuable, may make turn off some collectors from even chasing.
Another one would be timing. I find if I am following a toy line from it's infancy, I'll be more likely to be interested in the variants that get released over time. On the flip side, if I am just starting out collecting it, and it has billions of colorways, I'll be hesitant to care that much, but maybe over time as the collection grows.
I think variants and colorways, if used in controlled limited doses, are awesome additions to any collection. For me personally, I am a sucker for glitter.