It's that country's choice what they do. We don't get to say what they can and can't do.
And it may be that unvaccinated people can get a test instead - many holiday companies are already building these into their price packages, as are a number of resorts.
I've had one vaccine and will probably have had a second sometime in May. Dh won't have had both vaccines by then though as he hasn't had a first yet, so not like I'll be booking.
I don't particularly begrudge older people, health care and nhs staff and CEV people their holiday travel a few weeks before me though.
Tbh I'm just hoping we can go to Scotland at May half term so I don't have to move my holiday yet again!