I guess it's part of the Shepard fixation, which I just will never understand. The guy was cool (if you made him cool and applied some headcanon to fill in the gaps), but was really just a brick.
The bigger thing, which I do understand, is the loss of the ME setting. With a new galaxy filled with new races, we are leaving a lot of the stuff we learned/heard about in the trilogy behind, which is a bit of a pity. To what degree we're moving on remains to be seen I suppose.
Eh. I'm more optimistic about Andromeda than bothered about leaving the trilogy behind. Although I'm a tad disappointed we won't see what became of most of the Milky Way, if any, I'm not mad about moving to Andromeda. It is kind of annoying that the MW might be completely gone now though, thanks to the ending.