I don't know about more affluent, but the fact is that it is mighty convenient that each iTunes account is linked to an active payment card such as a credit card. In the old days, if you wanted to buy an app, there were potentially many steps you'd have to take: go to the app website, register an online account, create a password, type in your credit card number, wait for the email confirmation, copy/paste a serial number, download a new purchased app binary to sync to your device, etc. Not exactly inconvenient, but now all you need to do is press one button, enter one password, and it just happens. It is very convenient and very easy to do, which encourages impulse sales.
Will some people abuse the policy? Sure. There will always be people who look for loopholes, or download cracks or keygens. They were never going to pay up anyway. Will it hurt the sales from honest folk looking for good apps that are worth the money they paid? Absolutely not. In fact I maintain that it will help sales because people will be willing to take more risks on higher-priced apps, knowing they can get a refund if it doesn't work out.