I agree. On my V210 I have the older pro flight tower from '01 that was narrower in the back so I had a bimini made custom. My directions were "make it so a 5'10" guy can stand comfortably under it and make it as long as possible without interfering with the rope coming off the tower". My bimini is higher than anyone else's that I've seen, which may look a bit strange, but it sure is nice walking under it! Note that I have no speakers or lights on the tower (nor do I plan on having any).
One thing I would have done different is to go with telescoping legs. Saw a post the other day re: a custom bimini with these. Forgot who made it but it was in Nor Cal. I would love to be able to strap an inflated tube under the top of the tower but over the bimini, which I have no room for right now. It's rare that I leave the tube inflated (for my young kids and their friends) but I'd probably be more accommodating for them if I didn't insist on deflating the tube to get it out of the way every time.
With respect to your original question, I don't know if there is a "proper height", especially with the newer tower designs like the new Malibu one. The others I've seend have been around 5'6" from the floor based on where it always seems to hit me in the back of the head.