Lack of End Game Content

[Avraym]

... The Ultimate weapons had a single extra materia slot. That equates to an extra 40 additional Crit/Direct Hit—which is so minuscule you will never actually notice a difference. Regardless, Ultimate was never about the rewards but the prestige and challenge. You could literally offer nothing but the title and the majority of players who cleared would still have cleared. Being less inclined is entirely subjective. I got six of my seven clears well after the weapons themselves were pure aesthetic. It doesn't make a lick of difference to me because clearing Ultimate is the reward. Everything else is icing on the cake.

I would say, look at the statistics.

A LOT of people cleared O4S in contrast to Ultimate.

Ultimate was of course, more difficult, but the motivation to clear something that offers - as you've said, being so minuscule, players will have far less drive to complete it.

I've said it before and i'll say it again, the reward matters.