Door locks get replaced all the time. Some hotels have brand new locks, some are still rocking magstripe. The likes of VingCard already offer retrofit kits and software updates. If the hotel owner and brand wants to offer the feature they will. At least give them the choice.But making such a change would require millions of hotel door locks to be changed around the world which isn’t a practical reality.
Everybody updated their credit card readers to support EMV, then rushed to add contactless last year when we (in hindsight, mistakenly) thought COVID spread through surfaces. It's really not a barrier to adoption.
At least in the current moment, BT based door unlocking sucks. It doesn't work reliably, and a lot of owners (including Disney) neglect to put the Bluetooth modules on their common doors (again, Polynesian pool gates. Can't use the app to open that gate).