That is one result, the bigger picture is that the strategies centralized owners of those items use to make profits at the expense of each user would go away.
You are correct that an issue exists between completely hard-coded ownership on the blockchain and subjective creation of items in a game, but perhaps ruminate over some roadblocks. If a 'set' of items represented by NFTs is valued by a large group of users, then developers which do not integrate those items fairly enough will suffer users.
In this case it will not be the game developers controlling the items, it will be artists who sell the raw NFT which becomes integrated. This leads to all sorts of other little issues that aren't as fun to dunk on, but you should at least steel-man the concept.
Furthermore, your example of cosmetic items is the weakest example. Items which offer in-game functionality first and foremost, and are released according to semi-predictable mechanisms are the stronger case. Just like Bitcoin prevents unwanted malicious activity from allowing forks, so to must the game(s) which use these items. I'm not convinced it's so impossible to have an open source game built around the items rather than the other way around. An extremely simple RPG is a MVP.
Of course the visible community around NFT's today is completely ill-fitted for such a project, but like all things crypto on HackerNews, detractors often mistake the loudest sales-pitch for the best possible outcome. If you want to make a strong case against the merits of crypto, focus less on projects who spend their effort on marketing and more who spend their effort on development.