I dunno about that. You spend most of FC with a party of either 2 or 3 characters and rather limited options since most characters are still learning their moves. The fact that you get access to all characters' crafts right off the bat and have a party of 4 (that you can switch around pretty much whenever you want) for almost the entire game made me think SC was better than FC from a gameplay perspective, even if the pacing was more uneven than FC.
Yeah, I'm firmly in this camp regarding the comparisons between the first and second Sky games. Mind you, I rate the first Trails in the Sky fairly poorly as an RPG when it comes to gameplay, as I did not have fun with its actual game stuff.
That's literally the standard JRPG experience though. Slowly unlocking skill as you progress was what made FC fun, since you never knew what you's get next.
Meanwhile what does SC do to change things up? A barebones chain attack system and upgraded versions of their original attacks. Except the balance is fucked so characters like Estelle barely feel changed and she even gets nerfed!
It doesn't do much to change up the gameplay, although I think the option to choose one of two buddies for the first half is fairly notable, as is the ability to choose party members for most of the game.
However, where Sky SC excels is in expanding upon the first game. It's possible to actually choose combat different strategies, due to the greater party customization, additional quartz options, and the far greater variety of accessories. Technically, Agate still uses the same crafts, but his Wild Rage upgrade suddenly makes S-Craft spamming possible (not that it'll necessarily work that well against the final bosses). Mages, meanwhile, get massive benefits from the higher-level quartz and additional slot. Having Schera available for most of the game enables Heaven's Kiss craziness in SC, whereas Schera is locked out of the party for the majority of the previous game. The first game has Joshua and Estelle alone much of the time, so the strategy is often "Have Joshua use Dual Strike while Estelle attacks or casts a heal spell."
The other difference in the gameplay is that Sky SC has more challenging bosses than the first game, so it doesn't just provide the player with more customization options and ways to get strong; Sky SC also demands a higher level of mastery from the player to encourage some customization (I think the third game does even better, in this regard).
I should also mention that I dislike the beginning sections of RPGs, for the most part, when the player's characters are weak and there aren't many options. It shouldn't be a surprise that the original Trails in the Sky isn't that much fun for me, since the entire game feels like the first half of an RPG where the player is weaker and options are limited.