That's always been my take vs. at check out, probably for the same reason as the suggestion of tipping housekeeping daily vs. at end of stay (the appropriate person or shifts get the $$).

On a dif note. My one pet peeve re: tipping is (using NYC or Vegas as an example) is being expected to tip the doorman when there are a gazillion taxis lined up, all the doorman does is wave the next one forward & opens the door for you (and may or may not lean in to tell the cabbie where you're going). If I was being helped with luggage I'd have no problem w/ tipping him/her, or if the doorman has to go to the street & wave/whistle down a taxi for you I'd have no problem with tipping, but when all she/he does is wave the next in a long line of taxis waiting it bugs me. OVMV.

Cheers.