There is not, and this is not a problem specific to Legacy mode. Standard suffers from this as well; if you use the keyboard to turn the camera and then press forward it will also require you to complete a turning animation. This continues to be a problem even at 100% Character Turn Speed.

If the direction you want to dash happens to be in the direction of a particular target, you can macro dash in that direction using something like this:

Smudge in Target's direction, then automatically re-target last enemy:
Code:
/lockon on
/facetarget
/ac Smudge
/targetlastenemy
/lockon off
/micon Smudge
Smudge to specified target
Code:
/target <sometargettag>
/lockon on
/facetarget
/ac Smudge
/targetlastenemy
/lockon off
/micon Smudge
The /lockon is necessary to force you to face the target when moving. Without it, if you are holding a movement button, you will continue to face the direction you are moving and dash in that direction instead of toward your target, even with the /facetarget line. The /facetarget line is there so that if you're not pressing any movement buttons you will still dash in the direction of the target.