I'm afraid I disagree, the whole CT arc isn't just very similar, it's essentially the final 3 dungeons of FFIII ported to XIV, slapped some allagans shenanigans on it and called it a day. It's down to the very entrance to the tower.
Ivalice on the other hand can be actually considered a remaking of the whole ivalice alliance since it reworks most of the historical events to create what can be considered a new continuity to that setting only tied to the XIV setting and frankly it is miles better adapted than the CT storyline. Luckily we are getting new material to CT to actually rectifying those mistakes which were made simply because the game was new