"And all I loved, I love alone." –Edgar Allen Poe
(Though what you probably didn't know is that the Doctor said that and his friend Edgar Allen Poe wrote it down.)
They may have forgotten the man, but the strange blue police box is remembered.
It's frustrating for some, who cannot for the life of them ever recall ever seeing a blue box anywhere on their planet.
For others it is remembered with a misplaced fondness, that blue box must have been quite something, they're sure of it.
For all, it is quite the peculiar mystery. A box. A blue box. A Police box, that's blue. A blue Police box. There's obviously something more.
There just has to be you see, for strange things often come with strange people. And with strange people, strange happenings.
It is because they all remember the strange blue police box that they all wait to see it again. They wait patiently, the people of the universe, to maybe confirm or deny that they haven't gone absolutely mad, thinking about strange blue Police boxes.
They all wait to see the strange blue police box again, the people of the universe do, because they feel that there may be something that they've forgotten.