Have only three members in a party permanently was probably provoked by Secret of Mana (although I might be stretching here a bit) and is good for character development. (What I mean by this is that in most RPGs, you rarely even use the 5th to Nth additional available characters since you usually have your favorite 3 or 4 who rotate in your party). Bring back Mog as a party member (although technically, he is a weapon) has been enkindled by FF 6. So combine everything that was good about past RPGs and hope that you come up with another classic. This was probably the thought in the developers minds.
But they have also removed some of the better elements of FF13-1 such as item / accessory /weapon creation based on the Star Ocean series. Another element removed is the summoning of guardian forces or espers or eidolons or whatever you want to call them, that have been a final fantasy trademark if you will for a long time. And while having only 3 members in your party, and at that only 2 are characters, it can get a bit stale after just playing with the same members whose crystarium points have been maxed out. Perhaps if there were 10 characters whose crystarium points needed to be maxed out, then that would add to the game's replay value.
I actually think that the battle engine of FF 12 was the best among a lot of FF games. (Sure, it literally became auto-battle for non-boss battles if you have programmed it right). FF 13-2 also lacked an addictive side game like FF8's card battle. Sure, bring back the chocobo races. After a few laps, it just becomes boring.
And when will players ever get to control an air ship (or a space ship) and explore the world? (But since this is a time travel game, it might not be necessary, but they also used portals in FF XIII so I'm thinking developers are just lazy).
Now for the part of the game has me currently pissed off. And if you want to avoid me spoiling your fun, you should stop reading. Again I say stop reading this post. Don't say I didn't warn you. This is the first Final Fantasy game that ends with TO BE CONTINUED....
Are you kidding me? This idea was probably borrowed from Xenosaga, but in that game, players expected a 3-part series even before they purchased the game. I don't recall any other FF game ever ending with TO BE CONTINUED... and as an FF fan, I never want any game to end that way.
"We just want to make more money by making you buy half a game" was probably the thought in the minds of the business managers at Square Enix. "And we might not even release the 3rd installment on the PS3, but wait for the PS4". I have played FF since 6 and the skipped a few games such as 9 and 10-2. There hasn't been an FF game in a long time so I decided to pick up XIII-2. And if not for the story, perhaps its major redeeming quality, I would have skipped this game too.