The Doctor was used to passing himself off as someone else; his psychic paper made it simple, giving him legitimacy in whatever role best suited the situation. It was deception, but of a relatively innocent sort; it got him into and out of the places he needed to be, even if it did sometimes cast him in roles he wasn’t expecting.
Intuitive stuff, psychic paper, often plucking useful identities right out of the minds of the people he showed it to, but it solved more problems than it created so he continued to use it.