not having a preferences UI isn't just about the time to build the UI, it's about control, QA, and feedback. If your customer has to communicate with you to get a feature enabled, it gives you a chance to talk to your customer and get a sense of what they need the feature for, if it will work for their use case or the data they're working with, or if there's better features to offer them instead to solve their problem. it avoids the issue where customers randomly click buttons to see what happens, and then get disappointed when the thing they imagined might happen isn't what actually happens. And it makes them feel special because you've turned something on just for them.

by all means, build a UI. but click the checkboxes yourself.