Yesterday, I referenced and elaborated on Seth Godin's allusion to affirmative buying. Affirmative buying refers to the compelling reasons that customers buy a product, as opposed to the objections that non-customers voice as reasons for not buying it.
The notion of affirmative buying relates to the principle of focus. There is a constant temptation to broaden the appeal of a product to expand the size of its potential market. But broadening the appeal of a product typically entails making it less appealing to the most avid customers. The weaknesses of the product that limit its appeal to a broad market typically come hand-in-hand with the strengths that maximize its appeal to a focused market.
As an exercise, ask your product manager to present a plan to narrow the appeal of the product. In other words, ask her to consider the feature that appeals most to customers who are already the most excited about the product and turns off all other customers and non-customers. Have her present a plan for accentuating this feature and introducing new features that have similar appeal (and non-appeal).
Perhaps executing this plan would be disastrous for your product. But the exercise is worth performing just to explore what the focus of your product currently is and what currently motivates your customers. And there's a possibility that implementing the plan might just make the product so much more appealing to its base that they spread the word about it and increase the size of the customer base.