I think you're forgetting Jonathan Quick, and I think your point is good, which is why it's the standard argument, but I think it's changing.
The thing is, it's really hard to find even a solid/good goalie. If you have one, maybe you're better off than the team who's forced to pay 9.5 to their star goalie. ...BUT, the team IS forced to pay that 9.5, because the alternative is starting over and risking goalie hell. Few teams have endured the kind of goalie hell TB endured before they landed Ben Bishop, and I think that's why even those of us who cringe at this deal still understand it.
I guess maybe teams could trade their star goalies for lesser, but adequate goalies. Not even kidding--it might work. I just don't think that's ever gonna become the standard practice for NHL GMs.
One thing to remember is this really isn't the same as Price's 10m. Because that deal was so outlandish that, all these years later, he's STILL among the highest paid goalies in the league. Whereas, within a couple of years, Vasy's 9.5 is going to be outdone a few times, and, if current trends continue, by the four year mark, when Vasy is hopefully still in his prime, 9.5 is going to be the going rate of a really good second liner.
The deal will be bad if the cap stagnates or if something crazy happens with the new CBA. But salaries keep going up, and it's only a matter of time before 9 is the new 6.