Differentiate between a wreck and a bug. Bugs may be big, common, and expensive, but they don't invalidate the system as a whole. Bugs need fixing, a wreck requires a reimplementation. But seductive as reimplementations may be, they are usually a lot more expensive and difficult than one thought, and at the end they're still going to have bugs.

Wrecks require reimplementation. In politics, as in software development, one should think very carefully indeed before declaring something a wreck.