Let me start by saying that I have been a linux dev since 1994, and I think it is the best over all OS out there. The problem is that Linux is a very small desktop market mostly used by geeks, nerds, system administrators, and those that want to brag. Virtually all retail software houses have stopped developing for Linux because the users are spoiled and will not buy software. This is made worse by the GPL licenses of recent years and the federations enthusiasm to sue developers as a means to make money. Linux has cut it's own throat, and until they change the rules and allow developers to make money without publishing source code, it will stay a closet OS.
Mostly though, it takes a long time to port something like b4x to linux, and it is simply not a good return on investment proposition, and the hassle of supporting 2 code bases.
--- Jem