The biggest reason IMHO is that it was yet another GUI toolkit unrelated to Swing. It might have done better if it was more Swing-ish. This may be common knowl

The biggest reason IMHO is that it was yet another GUI toolkit unrelated to Swing. It might have done better if it was more Swing-ish. This may be common knowledge, but I want to point out that Java's biggest problem was and remains distributing the runtime. And it's on this basis alone that JavaScript has won. Swing is a good toolkit - Swing is still used by Netbeans and IntelliJ, and a handful of other popular tools. Both of those tools have good round-tripping interactive form builders. It's a lot of value, but yeah, distribution is so bad you can't realistically access that value. (Compiling to native with Graal is an interesting option.)