However fact remains, BW/Sorc remain lawnmowers that swallow pugs and churn out medals when facing unorganized pugs or enemies that lack HTL, Disrupt buffs and cleansing efficiency.
So the real hard question is, how to balance classes that still excel at wiping pugs, but become "lol at those dots" or simply cleansed when facing proper opposition. (any good healer will prehot on first sign of WoP or BB and begin cleansing).
More efficient Chillwind/Ignite is something looks tolerable, but uncleansable BB/WOP is just a bit too much, considering how extreme the damage is from that skill. A minor damage buff or additional debuff into VoT/SB is also something that might be tolerable without buffing the classes too much.
7 second max disrupt strikethrough is also over brutal, something that might be in the moral effect department, even then, it would also bring the class into total deathmachine for that duration, whilst outside of that timeframe very sloppy at dealing dmg at any organized opposition.
My counter suggestion: add 10% strikethrough into Staff wielding classes. Duel Wield gets 10% parry bonus, 2hander gets 10% block strikethrough; so why not give magical casters BW/Sorc/Magus/AM/Shaman/RP a similar type of benefit.
Considering you face currently 20-40% disrupt on average, (at times even harder if enemy has proper HTL + DeftDefender stacking going on), a drop by 10% into the total attack/defence calculation should probably give real efficiency of 7% gain.
And, the Disrupts are not hurting only BW and Sorc, but other magical casters as well. All staff wielders having same "buff" would not only benefit BW+Sorc, but also less played dps classes like AM, Shaman, Rp and even the rare Magus sighting.

This could be tested a few weeks, and if the amount of disrupt is still too damn high, then maybe modify it more, or then considering harder hitting dots.