I believe the key words here are "self service".

While there are desks for some Las Vegas properties at the airport there, I don't think I've seen an ATM type machine for hotel check in at any airport.

It is a good idea, and at some hotels it would be a vast IQ improvement over some of the front desk clerks I have run into, I do see some drawbacks. The first is can you get upgrades from the machine? Also if you have some special request, such as corner room, high floor, or quiet room, or if you want your room next to the soft drink machine or ice machines, can you request this?

Anyway it is a good idea, but I wonder how well it will be for some of us -ahem- high maintenance frequent flyers.