That depends on what and how much your product is.

For example -

A $10k per month email marketing service will need to go through many different stages of approval and have multiple buying influences involved.

On the other hand,

A $10 per month Gmail add on could be purchased on a corporate card or even one's personal card and then expensed.

Scenario 1 - no, building ONLY for the users is a bad idea because they aren't the only ones buying.

Scenario 2 - yes, the purchase is small enough to be handled by the user or at the highest the users boss (because they sign off on the expense reports).

We touch briefly on the subject in a blog post from last year: http://blog.voltagecrm.com/mapping-the-sales-process-part-36...

Hope that helps.