Retention is key to success for SaaS products. While acquisition costs are increasing and new alternative software is approaching every day, it is hard to keep your customers paying.
User experience is one of the best ways to boost customer retention rate.
When you look at the retention graph of an average SaaS Business, you will see that a large percentage of visitors are not retained at the end of the first week.
Horizontal Axis: Weeks, Vertical Axis: Retention Rate
There are a lot of reasons behind that, people are likely to search for alternatives(since there are a lot of alternatives for each kind of product or service out there) when their first interaction is not successful. Visitors tend to use the products&services which are discoverable and easy to use.
Good UX help companies turn visitors into users or even into customers because it encourages engagement with the tool. Sometimes the purpose is to close the knowledge gap and provide the required skills quickly to the users to make them learn fast and start benefiting the product&service, other times the main goal is to design a platform as familiar as possible to the other existing popular products&services, so that the user will start using it intuitively. These two can also be provided at the same time.
This answer is mainly based on what I have read and experienced so far about Software As A Service (SAAS) Business.