Perhaps they googled hotel and toothpaste :)

Very good question. I have seen this in all North American hotels as far as I can remember. I'm actually pretty surprised to see toothbrushes and toothpaste provided in hotels in Singapore, Malaysia and Japan!

There's gotta be some sort of explanation for this :)

For a weird twist, try asking the front desk for toothpaste.

I've had luck at three different hotels over the past few years (once when I traveled late the day the new liquids rules were enacted and TSA tossed my toothpaste; and twice when I merely forgot to pack it). It seems that hotels have complimentary toothpaste, but don't put it in the rooms. It's probably a cost thing.

I had similar experiences to dak, I found if I went to the front desk they would give you a small tube of toothpaste, but there wouldn't be any included in the room.

Perhaps it's because cockroaches, "eat household items such as soap, glue and toothpaste" [- http://www.answers.com/topic/german-cockroach]

That explains why they don't offer glue, too. So the real mystery is, "why do hotels provide soap???" ;)

I'm with you on this - it has really annoyed me on more than one occasion.