It needs balance. I've worked on products where ~90% of marketing resource is on retention vs. acquisition and they were getting outgrown by poorer products. And if you focus too much on what customers want to can limit opening your product to where the new users will come from. Or simply, customers never hear of your great product. With mass market products people often use whats put in front of them.

My experience (as a marketer) is companies tend to swing hard towards one philosophy. I'm yet to work with a company that treats each equally allocating resource between them on ROI vs. a general prefered philosophy.