Sometimes a small issue appears and looks like an easy, but time-consuming, fix. So it's flagged for later. Later just doesn't roll around until the system has grown three, four, ten times as big as it was when the issue first appeared.
Customers who are willing to put in their credit cards to sign up for a SaaS are invested in the system and have more reason to help it grow. At the beginning of a new system, these kinds of users are critical and getting the kinds of people who will do this it the difference between the system growing or failing.