Random thought... they have tube amps, solid state, modeling etc... why hasn't anyone made a system similar to how tube valves work but made with lighter materials and able to achieve higher watts for the space used? Let's get some egg heads and scientists working on that one.
people have tried, and they have failed. People are trying all the time actually but generally its not easy to do. Tubes are inherently flawed devices or atleast inherently poor in some aspects and its hard to develop a very efficient device that can emulate something so flawed. Its kind of a contradiction in aim