I find it hard to effectively state a rebuttal for a man with your credentials but I find I must do so.

1.)"Removing bands, and spreading signals over a greater span will provide that facility."
Wrong! Removing bands only removes current users. Much of the current bands in the lower frequencies are totally unsuitable for high volume multiplexed (multi-subchannel) digital signals because the wavelength is just too long to reproduce high speed digital streams! How can you produce even a single 100Mbps (Million bits per second) digital signal on a 28Mhz (Million Cycles per second) carrier frequency?
Answer: YOU CAN'T! If you attempt to modulate a signal faster than its carrier frequency it becomes a higher frequency signal all on its own!
So why destroy those legacy bands for the users? No good answer has ever been given by anyone proposing the destruction of legacy "HAM" and so called shortwave bands.

2.) "The radio spectrum, in total, spreads over some 300GHz, but we have only used around 30GHz so far."
Right. That is mostly because semi conductor technology is not up to breaking into the higher frequency ranges. Transistor response is a limiting factor in transmitting signals in Multi GigaHertz ranges, not government policy. When we have the technology we will move there. It is coming, albeit slowly, but these are totally new bands coming into use that have not been used before, not stolen from other uses!

3.) You hold up the recent conversion to digital TV as an example. I would not find that crappy move an example of progress if it was me. I had twelve channels I could receive with analog TV. All were viewable 24/7/365. Sometimes with a little noise in the picture BUT VIEWABLE!
Now I have twelve channels in my program list (Totaling 31 subchannels!) ten channels of which work sporadically or not at all most of the time. Try watching a movie in which you see ten minutes then for two there is nothing but digitized garbage video, blip, blip, blip of audio, then "no signal" for five, then back to blip, blip, blip, then maybe some of the show. REALLY ENJOYABLE ISN'T IT?
ALL of my neighbors are in the same boat. Its not just me! Better antennas, Coaxes, added amplifiers, rotors, HUGH EXPENSE! NO HELP! We are all fed up with it but what can we do? Now you're going to let the same idiots ruin my internet? THANKS, BUT NO!

Don't even get me started on cell phones! Someone calls me, we talk a few seconds and then I hear them saying, "Are you there?...Are you there?" or else there is dead air for a while while I ask, "Are you there?...Are you there?" Click, buzz. They call back, "Where was I when I lost you?" repeat ad nauseam until a conversation is (maybe) completed. Get a clue people! Its your wonderful, DIGITAL, phone, not my land-line, that is dropping the calls!
I used to have an analog cell phone. It almost always worked. I won't (and Don't!) own a cell phone that works as bad as every one I have had to deal with recently. Now you want to add that "reliability" to my internet too? No Thanks!

Do your dream work in the new frequencies that are opening. LEAVE existing, working, systems ALONE until you have your dream system WORKING, RELIABLY! And I can't stress this word enough...
PLEASE!!!!!!!!!!! We beg of you!