I just wrote my very first Ph.D. proposal. it’s about making a new UI that corresponds to user personality and preferences by not just looking at his/her profile but by scraping all available data from him/her all over the web. I think the final result can be super exciting and useful.
Imagine a UI that understand you are at work and hide some games and application from your phone. Or on a website that assumes you are on you’re studying and not disrupt your focusing time (for example Twitter not suggesting meme on that particular time). Or a website that from the moment you entered, for example, your email, understand that you prefer cozy dark theme over a comfortable, light theme.
Moreover, think about Netflix or PlayStation Store where if they could understand that I am on my off day and they can offer their new release or suggest to continue watching or playing.
All of the above can be obtained with lots of available public data but a system to aggregate all data with privacy in mind and let each user remove/add preference can be a huge improvement to user experience.