I understand your points as well, but the problem is the culture of "modding ROMs" instead of building Android distributions. That culture probably stems simply from the huge user base, many of which do not have a background in being interested in long term goals like buildable, testable, maintainable free software.
Or the problem is only a problem if you look at it that way, but for example I wouldn't consider any of these random blob:d mod-monsters if I'd be looking at Android. Replicant looks good but of course has a lot of the (real) work to be done.
Sure my Nemo Mobile for Nokia N9 or even Debian for my shipping-in-two-weeks GTA04 (to a very little extent) also have blobs included, but at least they're properly packaged, the blobs are separated, the distributions are build from the sources and are being maintained according to good practices. But of course they've the GNU/Linux background. I'd welcome a bit of GNU thinking to Android world as well. Not the manifesto but the culture of building long-living projects with beautifully building code.