To steal: To take (the property of another) without right or permission

Yes of course it is a steal.
Some customers do think that, because they have paid for a room, they have the right to take home some items (towels, hairdryer, spoons, sheets and blankets, vases, etc).
Most hotels are rather tolerant regarding towels steals, as it is not a huge cost for them (steals and damages count for less than 2% of operating costs), and it will be paid by the customer in a way or another (the price you pay for the room). They also consider it is a kind of testimony of their brand value (nobody may take back home a Motel 6 towel).
In some Luxury hotels, tea spoons are in very basic steel because the hotel knows that some customers want to "borrow" them, and most decorative items in standard rooms are good looking but cheap. In some hotels, towels have no name to make sure that no one would like to take back home as a (free) souvenir.