The demo of Final Fantasy XIII-2 didn't include any of the time travel at all - none of the changing of timelines to try and find new timelines that would let you create the timeline you really needed. So nothing of what makes it a great Chrono Trigger like game. And the reason the game wasn't "heralded" was because of how the first game in the trilogy was received, and the fact that it was the second game in a trilogy (I bet most people don't even know that FFXIII-2 is all about time travel and alternate timelines).
It's my belief that the game started as a true Chrono Trigger sequel, and then it was decided that, since their new strategy was to abate the costs of next-gen RPG development by releasing a few games in each RPG world, they made it into FFXIII-2 by putting in a (mostly) improved version of the FFXIII combat system and setting it in that world.
I played the demo and heard monologues of Lightning rambling on about time. It's the bad writing that plagued the FFXIII trilogy. That's why it put me off.
Also, that's a fault in and of itself that it's part of the FFXIII universe. If you have a story that feels completely out of place compared to FFXIII, that's a fault of the game itself. That's something that FFXIII-2 does poorly on.
And sure, maybe you think the game started as a Chrono sequel, but does that really matter? Just because it shares the concept of time travel doesn't mean it's great all of a sudden. Chrono Trigger and Chrono Cross are two games that are in the same franchise. If FFXIII-2 was as good, I would have appreciated that game too. But it's not.
As I said, I'm really well informed on the FFXIII trilogy. I don't need to play the game to understand if it's better or worse. It's fine if you think FFXIII-2 is great, but I think it's nowhere close to the Chrono games, and that's why I felt playing FFXIII-2 wasn't worthwhile.
FYI, I played FFXIII because I thought it was a good game from everything I had heard, and it ended up being good on my opinion. Can't say the same for FFXIII-2. I approached both games the same way.