Positioning is a key part of every job. Tanks and melee maximise their dps through uptime on the boss and by minimising travel time to deal with mechanics/adds. Ranged and Casters benefit from minimising movement and dodging. There isn't a job in the game which couldn't take advantage of movement tools such as gap closers. You can't really argue that movement and positioning problems are specific to casters alone.

Instead of creating a new gap closer clone for every job that clamours for it, why not just re-purpose sprint? Remove the TP cost, give it a set recast, make it oGCD, and have it make you dash forward a fixed distance when you're in combat. You could even keep its out of combat functionality the same as before if you just want to run around town or something. If anything, casters will like it better because you're cutting down on travel time and it would be easier to squeeze between casts.