So you're saying the entire purpose of the story is a nitpick? Really? The ENTIRE REASON the story happens is NEVER explained outside of datalogs.
I can't remember where it was explicively stated; since it's been a while since I played the game, but they do explain that Jecht got into contact with Sin. He was training in the ocean, near where Zanarkand was summoned, he trailed a bit too far off into the ocean and got into contact with Sin. Essentially Tidus was replaying what happened with his father; he would have turned into Sin too had Auron not been there to stop that from happening (They even explained how Auron stayed where he was.) Though, they didn't outright say it; they hinted it enough that Tidus and Jecht did indeed exist previously(You have to reason that one out yourself though). Their pyreflies were summoned back to Zanarkand; everyone in Zanarkand was called back. It's why Tidus' mom was in the Farplane (Since her summon died).
For comparison purpose; FFX explained that Zanarkand was being summoned by the faith and that Sin was being summoned constantly by Yevon as a way to protect the Faith and Zanarkand. The Faith were tired and saw the opportunity to break the cycle. This was fully explained and was the entire purpose/plot of the game. In FF XIII they NEVER explain, outside of the datalogs, why Bartandalus needed to kill everyone on Cocoon and Pulse. He needed all the snow things that are created when people die; a huge amount of those would have to cause the Maker to come back to get the souls en mass. That is never explained in the story and is the main purpose/plot of the game. See the difference between the two game's story telling? One actually has it.
Edit: " At no point in the game does Bartandalus explain that he's doing this to see the maker." I was wrong about that, he does say it in your clip. But I don't believe he mentioned it before that point, nor does he ever mention how the mass deaths of everyone on Pulse and Cocoon would summon the maker (Which is very important since they don't explain the door that Etro opens up to get to the Maker).
look i can't remember every single detail (might replay it soon to refresh my memory) but to me the overall plot was neat and made sense, i liked the party, pulse (cocoon part could have been better), gameplay, soundtrack had also nice tracks (for ex: oerba and sunleth waterscape), and wasn't bothered by ff13 liniarity. if you dig deep enough you might find some inconsistencies in the story but, at least to me, not big enough ones to kill my experiance. so let's leave it there.