Why does the Overmeld system work like a F2P game rather than a sub?

[Jinko]

I've seen HQ Overmelded gear with better stats than a lot if not all dungeon/tome gear. I've seen one piece melded with +24 Skill Speed (4x6 Skill Speed materia) and a +6 Determination.

My Vanya robe of casting has quad spell speed on it, but to be honest spell speed/skill isn't that great nor is determination.