More platforms would be better but the answer is for someone - commercial or some free software initiative - to get a usable and supported device to market, not making impositions on an already established platform with its own strengths and legions of customers who are willing to pay slightly more because of them.

Network effects. Or do we really expect devs to write proper code for 3+ entirely different native mobile platforms?

No, that’s why we need market regulations so that the two lucky platforms that won the game serves the people, and not only their wallets.

If only there was a way of delivery applications using a uniform set of rules independent of any manufacturer or vendor..

hmm what would I call that.... A standard perhaps..

Then maybe we could make that same application work on several types of devices and form factors that simply run that standard via a web of devices

We could call them Web Apps... A Web App Standard....