Should Skill Speed and Spell Speed still exist?

[Valence]

You will never see these stats combined because it would require redesigning old relic weapon stat distribution UI elements. Ain't nobody going back and re-doing the Sphere Scroll art because somebody wanted a stat removed.

You're right, that's also why they added DH to replace Accuracy when they removed it, or Tenacity to replace Parry on Battledance materia (which is funny and sad because it didn't change anything for that last one).