I love my 360g fibreglass tank. It cost about £650 (uk). An all glass tank would have been murder to install due to the weight and an all acrylic tank was silly money, that's why I went fibreglass. It took just me and my 14 year old lad to shift it into place, though it was cumbersome.
The big downside with fibreglass tanks, and it's twofold in a lot of people's eyes, is that usually there's only one viewing window and a lot of them are ugly rough things (and yes, those blue ones are hideous, mines black outside and in). Many people wouldn't dream of having them as a centrepiece in their living room. A shed, or a garage or other dedicated fish room where aesthetics aren't that important is usually a good place for current fibreglass tanks. Mine is in my fish room where not many people go, my 180g all glass tank is the showpiece tank in my living room.
I built a stand for my fibreglass tank whereas many would leave them on the floor. So my single viewing panel is at a good height for seeing the fish (all midwater, top level fish by the way, how rays or other bottom dwellers can be enjoyed in a fibreglass tank is another problem).
I believe the secret to moving fibreglass tanks forward is to have more viewing panels, maybe three in total, and deeper ones at that so bottom dwellers can be seen, and to make them easier on the eye so people would start to look at them as proper display tanks which could rival their stupidly heavy glass or insanely expensive acrylic counterparts.
Maybe the price would have to increase with more glass panels and the weight of the tanks would go up a bit but at the end of the day I think it's possible for someone like you, who's obviously passionate about this, to come up with a relatively lightweight and cheap fibreglass tank that you can see your fish in, from not just a single viewpoint. And the biggest plus for many people is that your design would look the part.
Then you'd have to go about designing, testing, producing, marketing and shipping them to the world, no small problem.