Mmhmm....so, by your logic Shady.... Hole-in-the-Wall should have something to do with a dingy bar. Or should dispense money ("hole in the wall"British slang for ATM -- though I think I'd rather say ATM, wouldn't you?).
But, no, Hole-in-the-Wall is simply a hole in a wall.... that you can pick up and move. Gosh, that seems silly and defies all reasoning but it doesn't have anything at all to do with the concept of a hole in the wall. In fact, all it really is is a plot device necessary for a puzzle later in the game that didn't fit in anywhere so they put it on the Isle of Wonder.
Did you have issues with Hole-in-the-Wall when KQ6 came out? Because by the logic you just argued, you should have.
Aside from that, in King's Quest lore -- you know, the rules of the world we're discussing -- it's meant to be a crazy illogical place that defies the laws of physics. It says it in the KQ6 manual:
http://kingsquest.wikia.com/wiki/Guidebook_to_the_Land_of_the_Green_Isles#PART_III_The_Isle_of_WonderIt describes just a few things that conflict with your theory...like talking sand grains.
Mostly I'd like to direct you to this quote: "But be warned those travellers who like to know, exactly what to expect from life would be well advised to go elsewhere."
If it all followed the laws of physics, you'd know what to expect. So, clearly, the Mag-Gnat is *not* in defiance of what the Isle of Wonder is.
Besides, as you JUST said... if the rules of the rest of KQ games don't apply to the Isle of Wonder why would the rules of anywhere else apply to the Isle of Wonder? That is what I like to call "the kind of logic that isn't" -- and for someone who's debating the logic of the Mag-Gnat, shouldn't you be trying to be logical?
Basically, what I'm trying to say is just because you don't like it doesn't make it wrong.
Lambonius is right also, in that the team has offered similar reasons to past issues which basically means "Oh we didn't think of this, but it's too late to go back and fix it". The "it's the Isle of Wonder" excuse is a lot less flimsy than some excuses they could have given.