The way it was explained to me was that Shadows compensate their lower (even with Combat Technique) armor with the increased shield chance granted by Kinetic barrier. In encounters where those charges are eaten up too quickly though (basically any boss that has frequent hitting melee attacks, like EC Kephess and supposedly Zorn) that defense crumbles, and the Shadow is at a severe disadvatage compared to the other tanks. What am I missing?
You're forgetting that a great Shadow tank doesn't just rely on their "standard" mitigation. A good Shadow tank is going to keep up KW, use TkT as much as possible to maximize self healing, and all of those other things that you do all of the time. A *great* Shadow, on the other hand, is going to know how and when to abuse the living hell out of Deflection and, especially, Resilience. Deflection is on a lower CD than Saber Ward and does pretty much the same thing; Resilience is on a ~35 second functional CD (thanks to Elusiveness) and can and should be used to ignore large F/T attacks (like Kephess's huge Internal DoT). Essentially, you're missing the way a properly played Shadow is going to completely ignore large swathes of incoming damage through judicious use of CDs.
Also, on another note, what is the official word on the 2.0 changes? I have read the patch notes, but of course I am not sure I evaluated them correctly. The way I understood for example the Shadow changes was that it's mitigation actually got worse (the 20% armor buff is removed, and Kinetic Barrier got a longer cooldown), but in turn she got other gimmicks like increase to the healing recieved and an encounter specific way to buff the healing output in general. Which seems to put the Shadow even further into the 'tricky and gimmicky' direction compared to the 'I just shrug it off' attitude of Guardian and Vanguard.
You're forgetting a few things.
First off, yes, KW got its CD increased (from 12 to 15 seconds), but it also got the number of charges increased from 8 to 15, which is a massive net gain. You're also forgetting how Kinetic Bulwark is going to provide a pretty impressive amount of additional Absorb over time (each KW stack you lose generates 1 KB stack, up to a max of 8, and they stick around until you use KW again). You're also overvaluing the 20% armor bonus from Stasis that got removed: CT already provides 115% increased armor, which means Shadow are going from 235% total armor to 215% total armor, which isn't a major decrease (it ends up being ~8.5% less total armor and a loss of roughly 1% K/E DR. Shadows are also getting what is, quite possibly, the best survivability CD in the game in Battle Readiness; currently, it's just a 10% heal with a pittance of increased self healing for 15 seconds, but, after 2.0, it's going to heal for *more* (15%), increase self healing *even more* (35% increased proc chance along with the existing 100% increased healing from proc), and provide 25% additive DR (which, combined with Shadow K/E DR, translates into the same equivalent survivability contribution as Warding Call) and it still lasts 15 seconds (pretty much everything except for a VGs Reactive Shield is 12 seconds or less).
It should also be mentioned that Shield/Absorb got buffed *massively*: all K/E damage attacks (which means all existing M/R attacks and a large majority of F/T attacks) can be shielded. As such, the massive Shield/Absorb advantage that Shadows have, and will *still* have, means that Shadows get more out of the Shield changes than the other classes do, even VGs.
A lot of people got hung up on the removal of 20% additional armor (which was a pittance anyways) and the increased CD on KW without actually paying attention the *massive plethora* of huge outright buffs that Shadows got. The buffs Shadows got are indeed *huge* and, honestly, I think Shadows are in an even better position than they currently are, especially now that Shadows won't just fall over in the presence of F/T K/E heavy fights.