As a reader I agree. For me it feels like reading a fic at a steady pace and then someone hitting the fast forward button and wham... it's over. Resolved, done but missing something ineffable. *shrugs*

As a writer, I do completely understand it. I may have (to a degree) done it myself *refuses to review own fic just in case*. And it could even be that as a writer, you had no clue how to end it, got some help from a beta and voila - ending. *shrugs* Still annoying... :)