For the same reason that open source projects are started by one guy with running code and not by committees talking about what to do. Everyone with an opinion isn't necessarily your customer - they are just guys with opinions.
You could be non-secretive without being interactive or not taking opinions. But that seems like burning PR early for a product you will be releasing soon anyway.
Do talk with people who's opinions you already value. But you aren't Microsoft so pre-announcing a product won't intimidate others into not competing with you and it won't whet potential customer's appetite. Make something you know you would use and then see how others like you respond.
You could be non-secretive without being interactive or not taking opinions. But that seems like burning PR early for a product you will be releasing soon anyway.
Do talk with people who's opinions you already value. But you aren't Microsoft so pre-announcing a product won't intimidate others into not competing with you and it won't whet potential customer's appetite. Make something you know you would use and then see how others like you respond.