That's nonsensical. Your argument means the decisions of the trilogy are already inconsequential since a sequel hasn't come along to expand on them.
Don't twist my words. The decisions of the trilogy becomes inconsequential because of the new setting. It's no different than setting a new Star Wars movie in a completely different galaxy, removing the Jedi, the Sith, all the cool technology like lightsabers, and all races save for a handful recognizable ones for marketing purposes. What the first 6 movies built up doesn't matter, because the new story is so far removed from the original setting that it's basically not Star Wars anymore.
The trilogy is a self-contained story that needs no validation from future games. Why can't the story just be the story?
A self-contained story still has to adhere to the setting of the universe. That's why The Force Awakens features elements from the old Star Wars movies. It doesn't just jump into a completely new story while treating the old one like it never existed the way ME:A is doing.