This is the real answer. Nintendo don't want to sell $1 games, because that would re-anchor Nintendo customers to lower price-point expectations, in contrast to the $5/$15/$30/$70 pricing tiers they have right now. But Nintendo just don't (or rather, didn't, until Super Mario Run) have the in-house experience working with mobile form-factors to produce even original games that would stand out enough from the dreck on the app store to be "worth" more than $1 to consumers. So they just didn't bother with mobile.