Been there :/ I'm not sure what it is, but it seems like hotel keycards are quite low quality devices, because it doesn't happen with credit cards.

Credit-card is imprinted once for all time; a hotel room key may be imprinted at any time, for each time a guest needs a new key. Presumably the "Read Only" vs "Read/Write" nature of these usecases confers a particular amount of robustness on the former.