When you're a company like apple debt is not a problem, in fact you can even sometimes get paid to issue debt if you're very very profitable. This is nothing like your monthly credit card payment, it's more of an accounting convenience.
Certainly made sense before when Apple had cash overseas that they couldn't touch, but what would the benefit of it be now?
See: GE, Sears, US Steel, Alcoa, GM, Xerox, Eastman Kodak, Kmart, IBM. All former giants that were laid low. The only guarantee Apple has, is they'll face a critical point like those companies did. Having $200 billion in cash with zero debt, will sure beat having $50 billion in net cash, when that time comes.
Apple should know this better than anybody. They nearly went bankrupt 20 years ago, due to their fortunes turning south.