A television I bought 6 years ago was with either debit or credit, and I am glad I did. I lost the receipt, and was looking around Wal-Mart with a month, and found a much better television for like 50 dollars more. When I brought it back to exchange it, the original television had dropped in price by almost half, and that was the credit amount they were going to give me towards the television. I said no way, and the manager went in the back and was able to pull up my information to prove what price I had paid.
If nothing else, look at it like big purchases give you a backup receipt.