Every time you do something a new way, there will be people in the industry who claim that what you're selling is no good because of X. (where X = something your product is missing, or does but shouldn't do, or some other supposed flaw)

If you believe them, it can be puzzling because you already know that customers have actually been more concerned with other things. Just keep going and don't pay too much attention to anyone except your customers and potential customers.