There can be; 31-tone equal temperament is a "popular" one
I think your approach is interesting, though. It's a different tradeoff than just mapping directly, and maybe more approachable in some cases. There are people who use midi controllers other than regular keyboards who may find it less convenient, but since your firmware is open source, someone could offer an alternative that behaves differently if necessary. The leap from microtuning with one kind of keyboard mapping to another is smaller than the leap from stock firmware to firmware which lets you browse the SD card for scala files and can parse them into arbitrary tunings.
It's your product and you are entitled to your own take on it; I am personally glad that you'd consider it AT ALL because it's not an attractive feature to most manufacturers, therefore people who are tuning-curious like I am are usually out in the code, not to mention people who come from cultures which haven't traditionally used equal temperament... Which is actually a lot of people, if you think about it.
And personally, I appreciate a synth that allows me to try new things!