The traditional argument on not allowing the camera to flip is that the map doesn't have a back. Riot can release a champ every 2-3 weeks, but doesn't have time to model the back side of a rock? This one's just lazy, and the idea that the audience can't adjust to the flip is insulting.
Another argument is that the problem only affects a small portion of the user base. How many users just couldn't adjust to the camera and gave up? I was close to it until I discovered TT and later Dom. I generally don't play SR any more unless dragged by friends - the other two maps don't require me to learn a skill I'm not interested in learning.
Even solving the visibility angle, the perspective on the camera makes fighting someone above you a completely different deal than someone below. With a centered camera, a nid spear goes off the bottom screen, but doesn't even reach the top. This makes learning ranges a pain, and I think favors blue team, since (in my unresearched opinion) people are going to learn the "up" range and cheat themselves on "down". I guess fixing that doesn't sell skins, but nudging it in a little would help a bit.
It's disheartening that nothing at all has been done on this. There's tons of things that could help: Flipped camera, BLC drifty camera, adjustable center camera, less angled camera, rotating the map to play left to right even. But nothing has even been tried. My favorite solution is the BLC one. You say it'd be confusing - have you tried it? The camera is just a couple vectors, how hard is it to prototype?