From the page you linked:

Note: Tickets cannot be purchased directly from ITA Software. If you find a fare you like, you can give the information from this site to your travel agent or airline when making a booking.

This is a deal breaker. I do not want to contact travel agent OR airline customer rep for booking my tickets. I want to find the best fare, enter my credit card and be done. Also, why should Travel Agent OR airline honor the fare which you posted when we all know that flight ticket pricing is highly dynamic?