Sometimes fees above and beyond the base price of your product are a lucrative part of your business. For example, late fees, though they purportedly are exceptional and merely for recouping revenue that would otherwise be lost, are in fact a major cash cow for video rental stores.
From a narrow economic point of view, such fees are good for your business. After all, business is about making money, and the fees bring in revenue.
But the long-term impact of such fees is hard to measure and may be negative. Fees affect the long-term perceptions of your product and company. They affect the equity of your brand.
For details, see this post by Roger Dooley on the Neuromarketing blog.