Mainly because nobody deserves it. Nobody deserves to receive money they haven't earned or to receive goods or services that they haven't yet payed for, doing so causes inflation and creates debts that cost buyers far more than what they are usually told. It's the very definition of fraud. The fact that everybody knows it doesn't make it right or excuse the consequences.
Usury. Considered immoral in some religions/philosophies. Islam, for example. Either way, it's optional after a certain point in life. I despise debt, and have worked hard to have none these past 15 years. Debt is so uncomfortable to me, that I was prepared to do whatever it took to avoid it. Paid off our properties as quickly as possible, no personal loans (ever), no car finance (ever), no credit card debt, no insurances (insurance is just as immoral IMO, because it plays on fear), etc etc. All it takes to avoid debt is to live well below your means ... for a decade or two. Few people are willing to do that.
You don't have home insurance? As far as lending goes, the world would be much, much different without it. Think about all the work that goes into building durable goods-homes, automobiles, appliances-all things which have usable lifespans of decades, if not possibly centuries. Whats wrong with stretching out the payment of a home over 30 years, especially if I'm going to live there for 60 years? Or 5 years for a car which I'll probably own for 20?