Yeah, readding slow mitigation kinda sucks, can still solo the same mobs but it isn't worth the effort anymore with the greater downtime. I don't mind it on the L60-70+ mobs in WoS, MPG, etc. Those are higher level zones where people should have to group generally. If they readded it to harbinger's or the lower level NC mobs, that's just lame. The mobs near zone in harbinger's are all light blue at L69, so they're like L54 or so, it's stupid to have these things mitigate slow. Haven't been to harbinger's lately, so can't confirm if they do or not, but others here have said they do...
Anyway, it just makes the little bit of soloing I do even more painful and boring than it already is. Most mobs in OoW don't seem immune to snare type effects, so I guess it's just melee soloing they want to make more difficult. Not like the xp was great soloing mobs that hit for 550+ to begin with anyway...when you can go to Droga or somewhere and kill mobs that hit for 160ish, with less hp's, that don't mitigate slow, and don't proc snares, DD's, and DoTs on you all the time. Makes OoW soloing kinda senseless by comparison.