I think these games shouldn't be sold as a package but rather separately, though I guess that would be the only way to sell King's Quest 8. While KQ6 remains my favorite in the series, KQ7 is a great game. It's got interesting and refreshing characters, great graphics and a fun story. KQ8 on the other hand is, well not very good. I honestly can't comment on the story too much because I don't remember it well and because I never finished the game. I do remember that it wasn't good enough to keep me playing with all the other flaws - bad graphics, and I don't mean fidelaty (i.e. polygon count), but rather the art direction, which was uninspired to say the least. Worst than that was just the bland boring gameplay. It was like a poor man's RPG or something - some weird mix of combat and adventure gameplay, that didn't work at all.
GoG, you're probably tied to publisher's request, but you'd do your customers a great service if you split this package in two $4.99 games.