It's kind of like the laws of science and engineering in reverse. In the real world, and even sort of in the sci-fi world, you consider the natural shape of the human body and build around that. But the snowspeeder doesn't follow that model. A human being simply can't fit into the speeder as it is designed and scaled. So the options are to make the figures smaller (ahem, cough, cough, Bandai, couch) or distort the shape of the human body to make it fit in the cockpit. Or leave off parts of the rump and the legs to make it fit. And if you scale the pilots right AND make them complete AND they fit, it's time to start checking the shape of the speeder for accuracy. They took the option of distorting the shape of the figures. Whatever.
BTW, of the original models, that's one of my favorite MPC/Ertl kits. Very recently (last time I looked) they could be had for $10 or so, and if I didn't already have a bunch, I'd be buying a bunch. And I would build most of them parked so I don't need figures.
Mike Todd