I wonder, have you played Crisis Core and Dirge of Cerberus? Or did you just watch Advent Children?
Yes I played both. CC was great, especially in combination with the anime clip about Zack/Cloud. DoC was a nice try, I did enjoy it somewhat - making a shooter from an FF was definitely an interesting attempt. I've seen better action-rpgs though. But there was more than the film and those two games during the VII rehash.
@PithyGriff: I've hyped VII because it's the first RPG I really got into during my youth and there's just so many great nostalgic memories of the joy I got from playing it previously.
As for VIII - I got into because I was kinda moody when I played it (fitting with Squall's emo-style ^^;) and I could get into IX aswell because I enjoyed the whole pirate thing and because it was more like VII than VIII. X I spent lotsa time on and it truly was a great game imo. XII had some good and some bad, same with XIII. I personally could never get into anything pre-VII. I tried I and VI and although it's shallow I couldn't truly enjoy it because of the shitty 2D. It's like watching a HD movie and then watching it's 60's black-and-white SD predecessor without the sound...
I think it's all down to Nostalgia aswell. Those people who played I-VI when they originally came out are gonna have fonder memories of it than the younger generation (of which I consider myself a part)...
And the Logistics of making the game would indeed be tremendously complex. The reason XIII is so "small" and linear is, as the developers stated, because it's all in HD. But meh, we can dream...

I really like the Materia system. I think it is by far the "best" FF system they've developed to-date. I do think it's lacking alot of materia effects, or special effects and more magic and what not. The Break Limit is also great. I liked it a lot more than the other crap they did in other FF games. We're talking about FFVII, not Crisis Core's Materia System..
I liked the Materia system back then and it most certainly beat FFVIII's draw system which was the stupidest thing ever (though linking the skills/spells to stats was a great idea). The fact that you could combine materia in the linked slots was very cool.
My favourite system is X's though. The grid was fcking excellent, XII's was retarded again and XIII's is a crap version of X's grid.
As for Limit Breaks, the fact that your character couldn't attack normally if the limit break was available was the first stupid thing. They fixed that in VIII though. Also, I enjoyed having to do something for each Limit break, like in X where you had to do Auron's combos or press X at a specific time (can't remember which character that was). The origin of this was Tifa's spinning wheels for her hand-to-hand combos.
I really enjoyed XII's Gambit System, though that wouldn't fit into a VII remake. However X's swapping characters in-fight, aswell as X's seeing the next ten moves (turn-based) are both excellent features that built on and improved the original battle-system.
On another topic, what about minigamez? How cool would the motorcycle game be in HD? Or snowboarding? Chocobo races could do with an upgrade. VIII's & IX's card systems where both very fun aswell, wouldn't mind seeing something of that sort integrated...
And some x-rated content would be nice too and I'm not talking about Chocobo-breeding

The perfect game... :>