I see it more as a retirement visa, but now you have to pay for your 90 day report. It's just a revenue stream internally. I've never seen anyone who actually needed medical treatment and couldn't travel have issues with the current medical visa scheme.
30 day visa exempt entry, yes it can be extended once inside Thailand for an additional 30 days. After that, currently there is a 60 day covid extension until january 25th available. There is no vaccine or plane ticket required for an extension.