Well said, Yahtzee! I'm sure you probably don't read these comments but i agree with what you said.
I didn't like the original ending to ME3 for the lack of closure but the Extended Cut does a fine job explaining most of it(the rest is up for player interpretation, something i think a lot of fans miss). For the record: In the EC the Mass Relays aren't destroyed, at least not in the same way we see in Arrival. The ending doesn't result in galactic extinction and the Relays CAN be repaired.
If you don't like the ending then you can feel free to disregard everything and write your own fan-fic(not all fan-fics have to be about romances) and make it your canon ending to ME3. Don't demand that Bioware re-write their own ending just to satisfy your vision.