I'm sure NRS is fully aware of this, but I think the variations system is great because MK is about story and characters more than most other fighting games. I'll elaborate what I mean.
In SF, people usually pick who they are good with. I mean, who would pick Rufus based on aesthetics (unless for hilarious or ironic reasons)? The answer is, people who find tier ranking or function more important than story and looks. Most of the competitive fighting game community shares that sentiment.
Now, with MKX the person who loves Sub-Zero as a character but hates playing defensively doesn't have to play a different character they don't give a shit about. If it's rush down you want go with Cryomancer. Want anti zoning? Go with Unbreakable.
Variations are perfect for MK because I know there are still a lot of people who like to main a character, not a tier ranking. A lot of us still main the character we picked up when we were 8 years old. Sometimes that character may have had shitty games, but like a football team (I hate football), you don't jump ship when they don't make it to the playoffs.