That's more I think that the business model was B2B and fairly high-touch-per-customer -- "are you a mobile phone handset manufacturer who wants to ship a MIDP Java engine for it? come talk to us about porting our stuff to whatever custom RTOS you're running on it". It was never intended to be direct to consumers or to run on hardware that an end-user would have the ability to install new code to. The Windows and Linux ports were there as the development environment/tools.

I think the main reason it didn't work out was that there was a brief window of opportunity where mobile was a thing but where there was a massively divergent variety of custom platforms and OSes, and so "we can port this to anything and it will then be a common platform for running games/MIDP applications/etc" was a potentially sellable product. But then Android and iOS came along and the whole mobile space coalesced into "there are only two platforms, plus web apps are feasible for a lot of cases, and it's pretty much all Arm", and the need for a middleware layer that abstracted away CPU and OS differences basically evaporated.