ranged attack on every monster?

[Kallera]

What new issue could have possibly arised from this?

Possibly Either kiting (Having the brave gladiator run around while the mob is picked off, with mere taunts keeping it running in circles.)
or binding.(-GA spamming camps, Archer firing squad.)

Druids in EQ used to only know soloing, taking high level monsters and dragging them around, getting tons of exp in one drop.

You could have mobs that drag the player back to them, give the mob provoke/hate reset skills, or raise resistance to bind each time it is applied. I'm sure there are other solutions.