[jpgvm]

There isn't the political will-power to make it happen and force all the browser vendors to agree and implement. Hence status-quo remains.

[afiori]

Which is ironic as the DOM interface was designed as an abstract interface (the IDL used in the spec is more interested in compatibility with Java than JS).

In practice though the main reason is that to have decent DOM bindings you need to stabilize many other specs first (unless you do a ultra-specific DOM-only extension, but nobody wants that)