The ham radio frequency allocations tend to comprise a larger frequency range for increasing frequency (also see this plot). For example, the 40 meters band is from 7,0 to 7,2 MHz, thus 200 kHz, while 23 centimeters is from 1240 to 1300 MHz, thus 60 MHz.
Of course, it would not be possible to extend the 40 meters band to 60 MHz since it would cover everything from LF up to 5 meters, but on the other hand, 200 kHz in the 23 centimeters band can deliver the same amount of information (in the Shannon sense) as in the 40 meters band.
For this reason, we tend to use more bandwidth-hungry transmissions techniques on the higher bands, but apart from enabling new applications, such as HAMNET, where we need the higher bandwidth, would this really be necessary?
Is it really only that there are less potential users per bandwidth in the higher frequencies or is there something that would make applications with larger bandwidth infeasible for low frequencies or ones with smaller bandwidth infeasible for high frequencies?
P.S.: Of course, I am happy about every hertz of available ham radio bandwidth and I do not intend to change the allocation. This is only a question out of curiosity.