Groups of Words made a very good point, Blizzard (or rather Ghostcrawler) has been talking to the Beta forums a lot, making posts at silly hours of the nights, responding to criticism and worries in each class (well strangely lacking in the Paladin forums). Its a breath of fresh air, but what does it really mean?
Simply that the best way to design something is with feedback.
Blizzard makes a point of releasing games when they are ready rather than based on commercial pressures (though one wonders if this is true right now) which allows them to try and get it right. The problem is that the internal testing staff at blizzard is small, at least compared to the potential number of testers out there in WoW. By opening up the testing early and getting people that don't mind testing buggy games they achieve a lot more testing on content, design, and strange oddities they never expected (Druids using an old tier set to get free instant tranquilites?).
So then opening up the testing seems like a good plan, however it has a flaw in that none of the beta testers have seen a vision statement for each class or talent tree and instead we get limited snippits from dev from time to time. By hiding (or rather not revealing) the overall plan Blizzard minimises the chance that we can give useful and productive feedback to them. Taking the Paladin, Warrior, Druid and Death Knight situation as an example; then we know the following:
1) all tanks should be main tank capable
2) no fight should be impossible with any combination of tanks
3) gimmick fights should be rare
4) tanks should overall be similar in survivability, threat and utility
1 and 2 really fall together, Blizzard admitted in TBC trying to make Paladins into Off tanks and AoE tanks (two roles the tankadin community tried to minimise as a strength but not one that meant your Paladin tanked everything to the boss then went healing), and Druids into off tanks and fluid hybrids. This decision being reversed makes a lot of sense given that both communities attempted to rebel and wanted to main tank as well as being supporting roles.
3 fits in with this as well, gimmick fights by their nature must either be trucusl such that not having access to the gimmick (for example using a non-protection Paladin on Morogrim's ads), or it must rule out 1 and 2 by ruling out another tank class as a progression tank. This you need to offer a gimmick solution to all tanks to allow then to at least survive the encounter reasonably.
4 is again vital, in tanking if one tanking class simply makes it easier to do an encounter, then they will be used, since we are aiming to make everyone viable this is a route that cannot be taken without an ability to offset it (so reduced damage but adding some trick to make the other tanks viable).
Problem is that this is about all the feedback testers have, so Warriors feel that other classes are getting all the main tank functionality added while they don't get enough AoE to offset it. Paladins worry for their AoE role now being better performed by Warriors and lacking mitigation. Druids worry for AoE, losing their massive mitigation and being itemized as rogues. Death Knights just worry, feeling squishie, lacking threat, lacking utility and so on. Some of these are justified, however a lot of the worry is that there is no direction to our worries, if we knew something akin to:
Mitigation: as Warrior, focused on consistent high block and "uncrushable" status
Threat: high, holy damage with very high threat multiplier, main threat through ShoR and Consecration.
Caster capability: weak, immunity through utility cooldowns, high number of overlapping escapes, sacrifices utility to use.
Group role: utility healer or dps, of role lacking due to reactive threat
Then we would have something to go ok, a framework for feedback rather than throwing darts in the dark and hoping our feedback and ideas come closer to the plan than not. Testing raw numbers is east, getting the class right isn't. Letting us in on the design process is great but I would rather have an idea about the path and the goal so that I can focus onto it and give constructive feedback on things other than numbers (which as GC mentioned are easily changed), and this actually help make things work rather than ending up worrying over nothing.