I really really dislike PS5's UI and I think you nailed why that is. I used to love booting up my PS4, seeing the activity, and idling on the dashboard to the beautiful Tetris Effect dynamic theme and music. I'd chill in my living room doing whatever else while that kept me company in the background (not like I was turning it on for that purpose). It felt... homey. And it was also much easier to get around quickly and find what you're looking for.
The PS5 dashboard is ugly, less intuitive than PS4, isolated, and either deafingly silent or heavy with depressingly low energy ambient music (easily darker and moodier than PS3, PS4, and PSV's default ambience imo). Not to mention bogged down, from the moment you turn it on, with marketing and low res splash screens for shit you don't care about. And not to mention the awful integrated PS Store.
The starting splash screen with the particles is so nice and opens with that happy little chime. I'm so disappointed they didn't follow those elements through the rest of the UX.