That would be cool, give each actual swing more feedback. Make jobs like monk feel even faster, too.
Could even use it from a balance perspective, I remember hearing how last expansion a Gunbreaker's damage depended quite a bit on if they crit Double Down. If Double Down, as the name implies, hits 2 times instead of just once, outlier runs where no hits crit (or alternatively, all hits crit) would be far less common. Hysho Ranryu (NIN's 1300p skill) could get a similar treatment, hitting 8+ times like BLU's Matra Magic. Would make "I got a lucky crit on a nuke skill" (Something out of the players control) less of a determining factor for damage, so things like if or when you hit the button would matter more (relatively).