Both traits are crucial for surviving today's wvw environment on a power build.
Even now, surviving a opening burst from a deadeye/LB ranger/hammer rev requires more than just triggering EM, usually needing to dip into other evades or distortion.
With a 10 sec cooldown on EM, you will practically never have it available when actually needed. Triggering it on accident because you dodged a ranger pbs, but leaving you open to eat a full rapid fire. It shouldn't require burning all your defensive tools in order to survive one weapon skill.
EM counter play already existed in the form of unblockables. Rifle warriors and LB rangers today are already adept at using their unblockable signets/traits.
Don't even consider surviving any scenario where you are +1 by someone with range options.
Blinding Dissipation was a tool to counter aggressive melee builds - why remove this from power builds in order to give condition mesmers even more potential confusion generation for those who run ineptitude?
Idgi, roaming power mesmer is a hard build, I do not see it survive as a solo viable option in wvw post this balance patch.