For instance, prioritizing on features to build/improve next. I have read support for both sides and can see issues in both. If you give customers what they want it could detract from the core focus of your product. I believe this is called "feature bloat." If you give them what they need they'll realize how valuable your product is to them, but there's also the chance of making a wrong assumption. How do I find out what they need and keep them happy? And is it an uphill battle to convince them that what they really need is more important than what they want?
I would suggest market research to ensure you have the most accurate data.
When we launch an update to our existing products or even a new line at Vital Consulting, I always make it a point to sell the experience and influence the customer of what they want.
Help them discover for themselves what their needs are and turn them into wants.