Hey man, dont' let it get to you too much. I'd highly recommend pulling back a little if you think this endeavor is too great in scope. Take a hiatus if need be. I know from personal experience that once I've worked for too long any one project, and the time spent is disproportionate to what the end-result is meant to be, I begin to hate the project and additional time spent on it is done begrudgingly because I hate to not finish something. I'm sure most are like that with pretty much anything, including you with this.
I didn't take you seriously at first. When you initially posted about creating your own specialized pixeling program, I thought 'yeah sure, this'll last for a few weeks . . .' But wow, look at you go! I have full confidence you'll have a finished release relatively soon. I think you've come to one of the best possible sites for feedback, so wise choice there -BUT- most of these guys are dedicated artists and don't understand your development process so I think you're wise again to have the discernment to know that their point of view most likely lacks the programming understanding you have and so the cascade of feature requests and disagreements is impossible to perfectly rectify.
You cannot please everyone all the time. So don't try. Unless you enjoy defeat. I think this is a life lesson applicable to everything. Why cram every perceivable feature into the first release? Keep your idea log running and plan expansions, new versions, however you to handle it, with additional features, but code your engine flexibly so as to allow for convenient integration later in the future. Who knows where this will go. It may eclipse Promotion and all the others.
My underlying point is a recommendation to you - Determine a goalmarker where you can cut off your alpha-phase and polish to something releasable, then implement richer features later.
(and to weigh in on the multiple colors thing, if it can be done smoothly, do it, why not? I like the concept)