I know JS is a lot better than it was 20 years ago and even half a dozen years ago, but it gave me enough PTSD over the years that compared to using JS for hybrid apps, Dart was such a breath of fresh air when I built my first Flutter app! I felt it made sense and just got out of the way so I could focus on what I wanted my app to do, and I didn’t even have to read any docs to start using it in Android Studio. And this is coming from having a lot of experience with compiled languages and a lot of Ruby in addition to JS.
And I don't particularly hate Dart. It's fine. I've written a lot of Java so it's not much worse. But if I had free reign to choose, I'd much rather take Rust.
Also, as a TypeScript/Swift/Kotlin person, Dart is fine; sure I’d like algebraic data types but overall it is good. The tooling (auto completion etc) is great. And it has a few cool unique(ish?) features like cascade and every class is an ‘interface’.