The idea was to have only a single plane that can do the jobs of several different old planes, which would make it easier to produce it in high numbers, get replacement parts, and train pilots and ground crews. Because that would be a lot cheaper and save huge amounts of money.
Oh, the irony...
It wasn't a stupid idea in the beginning, but at some point they should have realized that they can't actually build such a plane and cut their losses. Instead they kept hoping that those issues could be fixed if they throw a bit more money at it. Now we know: They couldn't.
Probably needs still just a bit more money to get it right.