I don't know why, but it pisses me of too. Probably that's because it's hard to assign bonus tracks to a certain album, I mean if you already have regular version, deluxe version, how you would call version with bonuses? Deluxe bonus track edition? So it's 3 versions of the same album already? Jeez, just put all the songs in one place!
The funniest thing is that Mark can assemble a whole new album just from bonus tracks. And he should, because of the sheer amount of people who hear bonus tracks and be like: oh, I never even knew Mark had a song like this. Probably the worst thing that music business offers these days.