The benefit of launching earlier far outweighs the annoyance of trivial feedback. If someone is genuinely interested in the product they'll be willing to overlook critical show-stopping bugs that destroy data in order to help you get the product to a point where they can start paying to use it. A few missing alt tags won't make the slightest bit of difference to the user, and that's the person who matters.

But failing to launch of a month while you 'polish' things will make a difference. You'll lose out on feedback, potential customers, and give more foothold to any competition. Plus it's boring and expensive to not launch.

People who'll walk away because there's a spelling mistake on the contact page would never become paying users regardless of how great your product is. Ignore those people.