They waited longest on Gain-DEX and Gain-INT for the reasons that they are going to be the best out of the "Gain-series".
Yes Boost-DEX will be about the same, but that effects everyone and not everyone wants +DEX.
Now inside yes we can use DEX Atma (RR/Omni), so DEX gear isnt as important, but outside the good DEX gear isnt for us RDM... Sometimes I feel like BLUs little brother always wanting the good DEX gear they get...
WHM Boost will be more thanks to /SCH and all the enhancing gear. /sigh
It's understandable prior to around ~lvl.60 RDM was on almost all the same gear as BLU being that they could wear Cloth and Light Armour, only especially since 75+ the same is not always true anymore.