"MIB: I don't have to ask. You brought them here. Still trying to prove me wrong, aren't you? Jacob: You are wrong.
MIB: Am I? They come. They fight. They destroy. They corrupt. It always ends the same.
Jacob: It only ends once. Anything that happens before that is just progress." //
I heard the contempt in MIB's words, the hope in Jacob's.
"How did Jacob's influence make his (Locke's) life better? It brought him torment and anguish on an island that eventually lead to his suicide."
The "flash-sideways-Locke" seems happier but haven't you noticed that he's still very troubled. He does nothing about it. Worse, he doesn't believe in miracles anymore. He's abandoned hope. (and getting married doesn't always solve problems.)
As for the "Lostie-Locke" that killed himself, remember that happened AFTER Jacob had lost control of the island, as shown by his cabin being used by someone else. I've always thought that the incident caused by Desmond's failure to punch the numbers in time didn't only make the plane crash but enabled Smokey to counter Jacob's defenses and take possession of the island, forcing Jacob to hide in the foot of the statue.
Jacob brought the Losties to the island but what happened to them afterwards was done under Smokey's influence. He may have also influenced Ben and the Others without them knowing they weren't following Jacob's wishes anymore. It would explain why Walt, who may have been Jacob's best "candidate", turned out to be too much for MIB to handle so he told the Others to let him go.
As for the rest, yes I expect a twist but not because we are being told Jacob is good and MIB is evil. We are heading down a path showing that believing in God is what brought misery to mankind and I don't think American TV is ready to make that statement...at least, not ABC's sponsors.