Why should the registry have to give you a chance? You didn't spend six or even seven figures on the application fee, development costs, legal fees, marketing, etc. not to mention the auction itself if there were multiple applicants. Why would they then fire-sale the good stuff to you?
Some registries feel that they can make more by having it be a free-for-all like you describe, generally these are registries with strings that can support hundreds of thousands or even millions of domains.
Some registries feel they can maximize revenue by premium pricing everything good and having fewer overall registrations, generally these are the ones like .tax where there might only be a few thousand domains that make sense. According to nTLDStats there are only 5,829 registrations in .tax. If they priced them all at $30 they wouldn't even be able to cover their OPEX, much less attempt to make a return on their investment, even though they might have twice as many registrations as they do now.
Most registries are playing domain investor instead of catering to them. Nothing wrong with that, it's their prerogative as the owner of the namespace. But I definitely wouldn't invest in those strings as a domain investor except when they miss something that should have been premium priced or price it incorrectly. I'm sure they don't mind though, they're not doing this to give domainers a chance to make money.
I still think it is worth tracking their sales though even if they are playing domain investor, as an actual domain investor can still hold domains in those extensions and would benefit from knowing of past sales. That said, I also wouldn't buy into the hype and go on a hand-regging spree just because the registry made a good sale.
