Those weren't power-level cost errata, those were misprints. This is a bad and inelegant solution.
I know that these cards were never broken; I just wanted to point out if Will's mana cost wasn't what was printed on the card it wouldn't be the only case of such a thing happening. Please explain to me why this is worse and less elegant than banning Will outright.
You don't seem to understand what's going on with SCG's image of Fylgja. This card has always been printed with a mana cost of W.
Check the January 26th Ask Wizards question and answer (
http://www.wizards.com/default.asp?x=mtgcom/askwizards/0107) for a clarification of what's going on with this. SCG is just using an old database image.
This would be the only case of such an erratta, and such an idea would be farcically inconsistent with the very philosophy behind errata. The only "exceptions" to this are when there exist cards that are printed with a different cost than other versions of the same card (Alpha Orcish Oriflamme, etc).
Katzby