Gun loadouts I can see but comparing MOBA items or talents to special moves in a FG is kind of a silly comparison. Two completely different games for a number of reasons.
Your overall point is fair, more skill expression tends to mean a longer lifespan. But it also has to be reasonably balanced. MKX died very quickly because while there was a lot of offensive options and cool stuff to do, everyone was unfun to play against and people got tired of it quickly. I highly doubt custom variations will be completely balanced if they do ok them, but that just means they need to balance them out with conflicts and other ways (if custom variations is the road they want to go down).
Agreed, it's a difficult comparison to make. It's true that these features helped those games cement a massive and durable player base, but their success doesn't mean it will work in a fighting game.
That said, I also remember when players felt that a consistent, level playing field was instrumental in the FPS genre. Unreal Tournament, Halo, etc. all gave players equal abilities, all guns worked the exact same, etc. CoD broke the golden rule and let players choose not just different starting weapons (and load out those weapons differently), but also select different abilities, like avoid radar detection, improved hip shot accuracy, use different killstreak abilities, etc. And this is another genre where fractions of a second determine winning or losing.
If NRS gets this to work in a fighting game, they could disrupt and evolve the genre the way we've seen other genre's improve over the past decade.
