What part of flash was bad?

- the (bad) sandboxing? WASM uses the same sandboxing model as JS, and thus provides the same security guarantees?

- the requirement of an external plugin? WASM comes preinstalled in all browsers.

- the proprietary aspect? Wasm is an open standard.

- the obfuscated nature? WASM can be decompiled very easily. Besides, js served by modern websotes are already minimized and obfuscated beyond recognition.

What am I missing here? I consider Flash to be a truly great piece of technology. It allowed easy creation of multimedia contents Its flaws were in its implementation, not in what it allowed. I want wasm to succeed as a reincarnated, better flash.