They've had built-in apps that you couldn't update through Market until recently-- Mail and Maps are two well-used examples.
While I agree with your sentiment that they should've employed at least a bit more forethought to this, this could motivate them to detach the browser from the OS (assuming that's possible), and push it as a standalone app on the Market where it can be updated independently of the OS.
What would be ideal, though, is updates for all OS components through the Market, similar to Ubuntu OS updates. Google ought to use this incident as leverage on the cell phone industry to tell them, "Look, we have to get security updates to the user ASAP, and we can't sit around debating whether they'll sue if something breaks on their devices."
But given their reluctance to indemnify anyone if their software breaks, I don't see them having much more leverage than a toothpick does on a redwood tree.