Charlie,
What has been accepted IS the Rema’s codification!
I’m not sure why you and Gavra At Work feel that a dishwasher’s relative low cost compared to a house is reason to disregard Feif Un’s rov’s p’sak that he doesn’t need a new one. For one thing, it’s his rov’s p’sak! (To quote someone who I consider to be wise, “And anyone who says you should do anything other than what your rav says isn’t orthodox.”
Also, some people I know stretch themselves quite thin (financially) when they buy a house, and that’s a time when they specifically need to pinch pennies.