My washing machine guarantee has recently expired. I know this because the manufacturer sent me a letter to to try to sell me repair insurance. Now, the selling of extended warranties at the time of purchase is big business, but I hardly think that those of us who refused in the first place are going to have a change of heart a year or two down the line.
The direct marketing spreadsheets will, presumably, indicate a positive cashflow on the excercise, but for the huge majority of customers who don't bite on this offer, the only message we've received is this. Your great product (replete with wonderful features and reliability) is now, in your opinion, a little bit dodgy and prone to expensive collapse.
I'm not sure about the ROI on that.