[Nanovelich]

Priest's Needles for the healing effect. DH's Marauder combo and Desperado combos; their entire Reaver stance really. Being able to actually get Cutthroat in just about ever (barring cheap 1m/2m methods of movement.) Kensei's combos. Literally any utilization of Charging Strike.

This is just what I can think of off the top of my head for what would be crippled by a 3-4m cut off only having really delve into a few builds, in addition to what Spoops already said. I'm sure that list could be expanded greatly by people who have played more classes.

It would require a complete overhaul in a lot of skills' setup conditions to be the standard, for certain.