1) I beg to differ between "didn´t work" and "is too weak". Shieldbarrier works on default on all types of damage. I agree, that it should scale slightly better with resolve or get a flat buff but it is far from "not working" or even "utterly useless". I am currently running around 480k health (flask + hp buff). With an average amount of resolve, my 60 rage Barriers will yield me a 60k-80k shield. That equals to ~ 13-16% of my max hp. I find that potent enough to justify its use.
2) Design intent is, that tanks need to rely more on externals, last time I checked. That some classes do not need to do so is not a design flaw within the warrior class but with other classes.
3) I agree that the two classes mentioned are currently stronger/not working as intended and therefore I enjoy seeing them being adjusted with 6.2. Stagger is significantly weakened, both in amount and mechanic (cannot stagger armor ignoring abilities anymore) and with the removal of the glyph, DKs will no longer be able to spam Sindragosa´s Breath.
4) Damage reduction and Absorption is superior to healing, since healing fixes something that already has gone wrong and reduction/absorb tackles the problem before it occurs.