The gimmick of trypio is downforce (basically), not flying, if you watch the anime. Understanding Aerodynamics or just trying it yourself would suffice.
Yes, it's called flying defense. I guess because it still looks like a helicopter, and because TT felt like it.
And they do have plenty of choice in a lot of cases (there is still no reason for modifying trypio like that, or putting hidden spirit attachment points on the AR's in plastics, or not making pockets "out of bounds" in their official rules). Again, they could improve the stadiums without those risks, and when beys fly out of hasbro stadiums, they generally seem to do so at head height anyway.