It's simple. If you want the system to evolve and improve you need to free up the developers time.
Makslane needs more $$$ so he can spend less time driving a taxi and more time improving Game Editor for his user base.
If you added up the man hours he has spent in development so far against how much $$$ he has made he is probably working for less than $1 an hour!
PS
So, when is the next build being released? Hurry up!