Not quite enough, I fear. I hope to be allowed to switch out some spells that are now unthematic (and much less effective) for my mage, too. (Not all, of course, he will stay with his charm/enchantment spells.)
I don't see where this was ever really a thematic issue. The ability to do fire damage on every single power is not a normally thematic ability of any class in 4E. It's an item ability.
And the other normally non-fire spells are -1 to hit and -2 damage (Hellfire Blood / Pyromancy Apprentice). That's not really "much less effective" except if the PC runs into fire resistance NPCs. And of course, this doesn't modify fire powers at all.
The Pyromancy Apprentice class feature is what WotC added that allowed for this combination. Combining this class feature with a Flaming Weapon meant 1 extra point of damage to wizard damaging spells and no fire resistance. This includes fire resistance versus ongoing fire damage.
PS. renau1g, this class feature is the reason they errata-ed the flame weapon and not the other weapons.
To me, the problem was that WotC erratta-ed the weapon and did not errata the class feature. It's one thing to have some damaging powers with this effect, it's another to have every damaging power with this effect.
The real issue here to me is that the PC was able to add this class feature (and hence hellfires blood, the intent of which is to give the bonus conditionally, not every time) to every one of his spells, even though it's fairly obvious that this was not the intent of the class feature. Now with the weapon errata, he cannot.
Btw, my PC Sheeva also got hit with the nerf bat. She had +5 defense vs. ranged attacks, so she stayed out of close combat and never took powers or feats to increase her defenses. Suddenly with an errata, she was almost as vulnerable to ranged attacks as she was to all others (+1 to defense instead of +5, about as devastating as -1 to hit -2 damage for some powers of your nerf). I could have replaced the PC because she lost her "sniper theme", but I just shrugged and let it slide and merely replaced the magic item. There are unbalanced game elements and I think that extremely optimized PCs here at LEB will often get hit with the nerf bat because they are often designed with some of the best combos in mind. It's a hazard of designing stronger more effective PCs IMO. I personally don't think that your PC concept (power-wise or thematic-wise) was destroyed by this nerf, it's just a minor inconvenience. An inconvenience that you can either use your "one time redesign" or a gradual redesign over levels to adjust if you feel that is necessary.
I don't think we should be putting in rules to allow massive PC re-writes, every time WotC errata's something. Massive re-writes require re-reviews of the modified PCs and judges are having a hard time keeping up with the current crop of PCs, let alone more because a player is unhappy with an errata. Especially considering that there are already "modify the PC" alternatives for the player.
Most PCs here got hit with the nerf bat sooner or later. I'm not (yet) convinced that we need to do anything about that, but I'm open to suggestions.