What they should do is for U/U items is make an upgrade system for u/u items. This idea could also make old content have use once more. Take the Blade dancer boots from Darkhold I think its like 3 dex and 3 evasion or something like that.
Basically what they could do is make you use items from the respective dungeon to upgrade U/U item's to make them better than materia items. So Lets take those blade dancer boots from darkhold with 3 Dex and 3 evasion and see what they could look like upgraded.
No upgrade: 3 dex 3 evasion
Lv. 1 6 DEX 6 Evasion
Lv. 2 9 Dex 9 evasion.
Lv. 3 12 Dex 12 evasion
Lv. 4 15 Dex 15 evasion
Lv. 5 18 Dex 18 evasion. ??? bonus stat. (5+ str)
Now the items to upgrade them should drop from the sub or main boss from the instance raid or open world dungeon or HNM. with this system you could make almost all the content in the game right now more desirable than it ever was.
1. This system would make U/U and U gear more worth while.
2. This system could make content last much longer.
3. Add's long term goals to the game.
Some of you might argue I could just dbl meld 2 evasion materia on my shoes but, you can't put dex on that. I feel that are plenty of good items in the game if only they had better stats on them.