Well, yeah, I absolutely agree. Replaceability and maintainability go hand in hand in a system. It's a cruel irony that the code that sticks around, often sticks around because it's crap.

(that doesn't stop me from sometimes having a weird admiration for incomprehensible software kept going forever with weird hacks. It's like with movies, sometimes they're so uniquely awful that you have to admire the art of them)