So I get home, patch up and immediately go into an AV. Fel Armor didn't get dispelled every time I encountered a Hunter. It was a wonderful feeling and I'm sure Mages feel the same way. I'll admit it will royally suck when Mages have an undispellable Mage Armor that reduces the duration of all magical effects by 50%...but it is what it is and I think it's a change for the better.
On that note I truly believe the undispellable nature of self buffs needs to be extended to other classes. Any long term (which I would consider 5 minutes or longer) self-only buff should be undispellable. Why? Well, as I see it if a buff is of a long enough duration and is only able to be cast on oneself then it is an aspect of that class that should be considered permanent. These types of abilities are intended to cover up glaring class weaknesses or buff up a class strength in order to effectively compete. To simply be able to remove one of these abilities is just silly.
Omen of Clarity
Wouldn't that negate the ability to dispel for other classes? I don't think so, really. Dispelling will still continue to be a valid tactic for short-term and non-class specific buffs. PWS, PWF, Paladin Blessings (on that note Paladins would do well to get a self only version of BoW since they really *do* need it) Earth Shield, MotW, BoP, Innervate, Eradication, etc.
Again, I simply feel that the long-term self buffs are far too vital to a class' performance be so easily removed. I would not, however, be opposed to Mass Dispel effecting them as it does require significantly more effort than spamming Purge, Devour Magic, Arcane Shot, etc.