I don't think the problem is the money. Neither of them provides a long term stable API, let alone ABI. So progress gets reset on a regular base.

Gnome is further hampered by no respect for user choice. They provide an appleish UI, with an Enterprise, one size fits all experience.

KDE is better, but they are not the official GNU/Red Hat choice. They will choose practical above esthetica.

A big part of the Linux success is POSIX, a standard to provide direction. The UI world never had anything line it, so it is very fragmented. A real solution could be a complete enough UI standard, used by OSX, Windows, Gnome and KDE.