You might think you know your product best when it's a problem you're solving for yourself. But it doesn't hurt to learn more about your customers.
One of the hardest things for an entrepreneur is to look themselves (their business) in the mirror and take an honest assessment - how do i look?
Finding out the big idea you had won't actually be used, or that your product stinks is not what anyone wants to hear. But this is exactly why we need to hear it.
I can guarantee you - No one has got it right first go! No one! Trust me - they may make it out that they did but they didnt. They had feedback and they listened and learned.
You can build a business (and a product) in one of two ways:
1) build the product - hope you get it all right, build the business model and go-to market plan - *hope* you get it all right.
2) save yourself a ton of time, and do some unbiased LEARNING customer interviews. Listen and adapt, change where you need to change, find the patterns, and come up with a better product and better plan. Then repeat, go through the entire process again (so painful i know) but do again and validate and tweak a bit more -> then go a build it.
These interviews may seem like a waste of time but i guarantee you they are not. Every minute you spend will save you time. Plus it adds so much validation, instead of saying "i think blah blah blah", you can say "when we spoke to ACME, John, and Sam, they said they need blah, blah, and blah". Speak with the voice of your customer, understand their world better than they can, know them intimately, and solve their problems!