Should the Casting Timer be removed or reduced for better DPS output?

[DPZ2]

Or Alternatively

Let Magical Ranged DPS Cast while moving so that way they don't have to facetank everything and be able to handle AOEs better.

So, basically, turn BLM/RDM into BRD/DNC/MCH, complete with a reduction in damage that is a distinctive part of that "moving" bit?