No it's not. Tank gameplay is frustrating in vanilla classic, warriors for example are constantly rage starved and lack the rage buffs and control that they get in later expansions. Paladins can't even taunt. Making tanking more appealing by making it less frustrating will go a long way in making the game better for everyone by making tanks more numerous. Giving a mages a heal is a solution to a problem that doesn't exist.
perhaps I misinterpreted what you meant, but what you said was the only real class balance issue in classic is tanking. This is a silly fucking notion since warrior is the only tank class in Vanilla, anything else is a stop gap for leveling/dungeons. That's all this really is too, shaman/warlock/rogue tanking, stop gaps for leveling/dungeons/pugs, adding a bit of diversity/class balance changes to the vanilla experience, especially the leveling up experience. I have little doubt that warriors will remain the premier tank at 60/raiding. Though with TBC/Wrath era class abilities what I do expect is the other classes to be fairly represented as DPS in raids instead of warriors also being the premier DPS at 60/raiding.
For the record, the problem with classic IS class balance, it's fucking atrocious for everything. DPS, healing, and Tanking. Every raid is 25 warriors, 5 priests, ~5 paladins/shamans, and then 1 of each other class as they are fucking useless. Horde tends to lean heavier on shaman and lighter on priests but that's because you have to have a shaman in every group, not because shaman are better healers than priests.
Also have you ever played WoW or any other MMO? you seriously think that lack of healers isn't a problem? it's almost as bad as lack of tanks. Giving heals to a popular DPS class is the solution to one of the largest problems that absolutely does exist, the same as giving more classes the option to tank. making it readily swappable runes rather than talents is a fantastic solution as well, since we don't have dual spec yet and Mages won't have talents for healing even if there was dual spec.
I wanted to give you the benefit of the doubt but i'm struggling. Pretty much everything released so far for SOD has absolutely been answers/solutions to things that everyone wanted.