Make a "custom version" for some customers is not easy. I doubt you can go to Microsoft and say "hey I want exfat on X devices but we are not sure how many devices yet". My guess is they have to buy licences in "packages" of X thousand not per/unit.

In this case I think they have to choose exFAT or not exFAT on all devices since it low volumes we talk about.

But for me most important question is what stable filesystem works best on optimized for flash memory without corruption. If there is a good open alternative I personally prefer that. But question is if there is... So maybe exFAT actually is best solution even I personally hate SW patents...

Btw... Even if its not fully comparable. But lets look at the desktop market. Even if a company will not use windows in the organisation you have to buy Dell/Lenovo/HP computers with Windows OS junk preinstalled. That sucks bigtime too. But what is the alternative? There is probadly zero companys selling bussiness computers without windows crap preinstalled... Atleast in sweden. (Yeah I know there is system72 in US)

My point is whatever you choose you never get rid of the facts that you have to pay Google, Microsoft or some other big corporation whatever you choose. Business as usual...