The theory on mentos has always been that as instances get tougher, the mento rewards go up. So, HOTO gives you little, Origin little more, HOS little more, ZS/DL more, and so on. It has to more with difficulty than levels - DOD has L57 gear, but it is much easier than L55 ZS/DL - so you get less mentos in DOD.
So, what is supposed to happen is that higher level people farm tougher places and get more mementos; and so earn stats at same rate. Problem is that DOD and GCE are still only real farmable memento places (unless you are OP enough to do fast RT farming runs). Running DOD over and over for 420 Tomb stat was bad enough. Make it 700 Eternity stat, and it becomes mindless grind.
I would say a new decent mento farming instance is what they should be shooting for. That means no Tias, Jennys or golems requiring you to run through 2 tornado rooms as first bosses.
-- Rustyx --- 92R / 92S / 92M on Reni (Guild KnightShift). Yes, running the new FOTM R/M, cause I am not elf enough to be WD/S.
Oh, and people who have more than 3 classes are clinically insane.