He's in charge of design, and design during his tenure (even before Liquid Glass) has increasingly had usability issues and bad design choices.
To be fair, iOS 18.5 (the latest public release) is pretty good, IMO, and what they are aiming for with LG looks promising too, so I would wait till September before giving up on it.

Meet Liquid Glass - WWDC25 - Videos - Apple Developer
Liquid Glass unifies Apple platform design language while providing a more dynamic and expressive user experience. Get to know the design...