It's not really the speed, it's the contribution from auto-attack that's really different.
Auto-attack matters a lot in FFXI and FFXIV, and it's actually what the combat mostly builds off for a lot of jobs (since it gives you TP to use the powerful skills). In other MMORPGs, auto-attack is mostly passive damage that your character deals, while you perform active abilities that may or may not be tied to some resource system, but these skills are usually not related to auto-attack in any way.
EDIT: Beaten by Grey.
XI Wiki



