The primary benefit to the developer is it can prevent a distraction and waste of resources on something that may not take off as well as show you a different application of the solution that you may not have considered though customer feedback.
For the past 4 years I have been building a Keyword Management System and many of the features came from users who wanted something more and I used that feedback to expand and adapt the application. That experience and that of these other new tools have shown me that the customer is not always right and that a lot of care and feeding needs to go into a MVP process to help educate and nurture the growth of the application. Many of the experiences I detail below are a given but some of the other feedback and experiences were totally unexpected.
Different Approach to Similar Problems
Frame of Reference
Audience Applicability & Feature Importance
That moment of epiphany that they realize this is a cool tool and they need it is critical to capture people. For example, after the diagnostic presentation when I had multiple people engaged who wanted access to it. However, I did not want them to see all my client projects so it took about a week for me to add the access and account segmentation which lost valuable time. In the week that followed, when I emailed people the access nearly half did not try it. They had lost that urgency they felt in the moment at the event. That epiphany at the event was an emotional needs connection that you cannot replicate later.
Now if I release a tool I have a link and sign in for it immediately to catch and keep their attention. In my own tests I found that it often takes someone 5 to 7 days to log in once they have access and more than 3/4 of the people who ask for access never login unless they are directly prompted. For my HREF Builder tool only 4 of 10 people who specially asked for access ever logged in and ironically, 2 of the people review tools and one writes primary about international search never logged into the application