I would rather have power cards restricted instead of errata'd. Errata should be done to correct templating issues, not to nerf a power card. If something is too powerful for the environemnt, or skews it to far, restricting that card is a good solution.
I recently rebuilt my Martell deck and added a second TVB, which sped up my draw considerably. 7 cost isn't that hard to get these days. And I'm actually glad that it got restricted -- it makes it more challenging for me to build a deck.
I can also see a day when the word "Restricted" is added as a keyword. Designing a card to be restricted isn't necessarily a bad thing.