This story might be complete bunk, but it was told to me who by my friend who was a professional BMX racer...
Do you notice how the head tube seems a little bit unusually long?
Well in the early 80's a lot of BMX frames had the problem breaking at the head tube. They didn't realize at the time that the reason they broke was the gusset made the frame too ridged. So they came up with the "MooseGoose" with the idea that a super long head tube would make the frame much stronger and harder to break. And they also thought Adults would want to ride these crazy kids bikes if the frame was taller.
For some reason they thought they were going to sell millions of these things and ended up only selling a handful. So they were left with all this precut tubing, and it was going to cost a fortune to re-cut all this extra tubing.
Well I'm not sure who but some genius actually invented the classic 80's scooter to use up all this extra tubing.
Now this is speculation on my part... But I've always wondered with their MTB's if they still hadn't gave up on the idea that a longer head tube made for a much stronger frame and incorporated it into the design. Or just like the scooters they tought it was a good way to get rid of this extra tubing?