I find it somewhat depressing that emailing folks about domain names they're not using results in either a) being ignored or b) being asked to pay $40,000.
I'm of the view if you're sitting on names that you're keeping around exclusively because you think they could net you a windfall in the future then you're a bit of an internet twat.
I think the new gTLDs are great. Most of them aren't exorbitantly expensive, and generally speaking they free you up to have an address on the big wild internet that makes way more sense than the contrived naming conventions we resorted to using in the past (eg: get[???].com, [???]app.com, both of which I can think of prime, famous examples in real world use). Is [???].app really better? Yeah, probably.
There isn't a good alternative to the way it currently works. Allowing domain owners to sell their domains results in domains going to those companies that are successful enough to afford them.
Some domains that appear unused are actually being used.
I've got a very minimal, largely neglected, web presence on my domain, but would not even consider selling it unless the price was very very high.
That's because I am using it--for email. If I were to sell my domain I'd have to update my information with thousands of sites, companies, and individuals.
That's not something I'd be willing to undertake lightly. Any place that has my email that I forget to update is a place where my account could be easily hijacked.
I think you're confused, and probably mean "give up the domains" they're not using. Not "give up the TLDs".
This is not a viable option, though. Even though someone may think they're not using the domain, there's a good chance they could be using it (like using it for email even though the a record doesn't resolve to anything) or they could be using it as an investment.
Asking someone to give up a domain that "they're not using" is like asking someone to give up the vacant lot they're not using. It's real estate.
Anyways, I'm actually arguably in favour or a Land Value Tax. Land is a super fininte resource and holding onto it for no reason other than as an investment screws over anybody who isn't there first. This is great if you have land, for whatever reason, but not to great if you grow up poor and want to live anywhere near your place of work in a place like London where the property market is completely broken.
The domains landscape is similar, except that it is indeed easier to create new TLDs than manage the mess of domain speculation.
What if you're a bank and somebody gets a TLD like "yourbank.bank" with valid SSL and starts fishing people from yourbank.com?
What happens now? It's not like there's a single domain already - there are dozens, if not hundreds of TLDs.
The realistic answer is: the new TLDs don't matter, even just with .com, it's easy to get a similar enough domain that many people will fall for.
Either that, or they'll finally realize it's futile and stop that nonsense.
The new TLDs are a massive problem disguised as a solution in search of a problem.
Who benefits?
There will be a time when the multitude of TLDs won't bother anyone. Limiting TLDs doesn't add security. Educating people about the dangers of the internet does.