As parent is an actual user, I guess they'll be able to tell if the UI pleases them.
Edit:
> UX used to be driven by researchers like Bruce Tognazzini and Jakob Nielsen, who absolutely did studies with actual users to drive their designs.
Large [UI driven] companies still do this or hire agencies to do so (of which there are far more nowadays given the field is more mature). The fact that UX researchers haven't much visibility outside of UX -- Nielsen started blogging relentlessly at a point in time where there wasn't really anyone else doing that, and it was hoovered up by a wider audience that needed that knowledge. That doesn't mean in any way that he's unique, or that companies who can afford UX teams don't do this. Nielsen and Tognazzini -- they were popularisers, good at producing easily digestible writing for a general audience
> If a UI designer can change an interface to please me a little more, that’s a good thing.
Without observing actual users, how do you know if you are pleasing them, or just pleasing yourself?