You've hit the nail right on it's head with this.
I'd also like to add something that ties in with the "easy to learn" argument. I've played quite a few skymines and the players it attracts are the very young and non-english speakers, I've seen many people who don't even seem to know how to use...
I may have an idea why.
From what I've experienced, skymine players are often illiterate (I rarely get replies from skymine players even if I send private messages) or just younger children (I've also encountered non-english speakers). They might have a hard time understanding the "High effort"...