And all this time I've been racking my brains to figure out where in MusicBee Preferences Discogs is disabled! Perhaps you should change the language used, "Discogs disabled in Preferences" because it makes me think I need to apply a setting somewhere.
Anyway I don't mind having to register MusicBee, I like the ease of use and simple approach but I'm no idiot, I can go online and check a box if necessary.
As for getting better artwork from other sources well I think for each of us "Your mileage may vary", many times I can't find the appropriate artwork and I have no choice but to go manually find and add some, especially since Google's source rarely works the past couple of weeks. So having as many options as possible is my preferences. If there are users who honestly disagree then perhaps leaving it up to the user preferences by way of an enable/disable option would be better than just removing the whole thing.