Then you're not looking at what people are talking about, people are upset at - every - aspect of the ending. There's A LOT wrong with the ending, as I said a black screen would still have 0 closure, 0 answers to any questions, etc, and somethings suck about the ending like the mass relays being destroyed.
However, the most important thing to me personally about it is the glaring plot holes in the story that make the whole trilogy a waste of time (story wise that is, the combat/quests are fun).
The fact that there as so many people complaining about so many things, means the ending is flawed in not one way, but many, many ways. There's a lot of bad things in the ending to choose what you want to complain about, after all.