Politicians get their kicks elsewhere these days and are thus reluctant to fund a folly with no scientific value that doesn't even give them any leverage at the negotiating table.
And btw, since there is no scientific value in sending bozos to the moon (or any other world for that matter), the question is a political and sociological one so you should direct your question to the appropriate forum.
They might go back to try our their Mars vehicle. It is a lot easier to test a Mars vehicle three days from Earth and in lower gravity than it is to test one 8 months from Earth
They don't have enough funding and they have not had enough funding since the Nixon administration.
People will return to the Moon only after those that control the money decide that there is something there worth learning over what is already known and it can only be done by manned landings. This is not going to happen next week or next year.
NASA actually has plans to; they have initial designs for a new lunar lander, compatible with the new Orion capsule (Look up LSAM on Google...), and have suggested a lunar base.
The problem is the United States Congress... *They* control NASA's purse strings; they dictate which programs are funded, which ones are shelved, and *how much* a program gets....
So, it's not NASA that doesn't want to go back to the moon.... it's due to our politicians. Want to help? Find out who your representatives are, and write them... they all have web sites; be polite, be firm, and let them know you'd be far more likely to vote for someone who would *expand* NASA's budget than someone who wouldn't...