You have a great idea and you need to get the MVP or the product shipped before you lose your competitive advantage or before you're out of money...
But even on the best of days, product development is about making a million different strategic decisions and navigating real life constraints...
You don't want to waste time talking about buttons, colors and UI things you don't really care about. You need someone who will help you align your goals with the real needs of your users and design viable solutions that will get you there.