I disagree.

I know of no law requiring a person to carry "picture ID". When you are asking for something that has age or nationality requirements attached, I can see being asked to prove age or nationality, but most hotel rooms do not have such requirements.

There is no excuse for a commercial business engaged in interstate commerce to make such a demand. Nor am I aware of any legal basis for such a demand.

At the risk of getting this whole thread banished to the cesspool known as OMNI, saying "better get used to it" when someone makes such outrageous demands is not the answer. That's the way rights are lost. As the OP noted, we are not yet a totalitarian state where officials can demand to see "your papers" any time the whim strikes them, and that applies with even more force to regulated private commercial entities.

It does not seem to be a Starwood policy (or, if it is, most Starwoods are not following it) to demand ID as a condition for check-in, but perhaps Starwood might want to consider making it a stated policy not to demand picture ID without valid reason.

OK, I'm getting off the soapbox. I'll go quietly.