Wasn't there at least one movie, where that was not a good thing?
There was. I think it was titled "Moonfall", or maybe "Another Earth". There is also "Oblivion" in which the Moon was partially destroyed. There are probably other ones, too, but I think "Moonfall" is the one to which you are referring. I might just give it a watch in a bit!
But yeah, it would not be a good thing, according to the movie at least.
Counterpoint: in Despicable Me the moon was shrunk and brought down to Earth with almost zero consequences... so maybe it would be just fine!
Seveneves by Neal Stephenson was a good book that goes into what happens when things change between the Earth and Moon.