Second, your ability to ship the coolest new client-side technology isn't being held up by TC39, or by the HTMLWG -- nothing we or they could do would make MS ship IE 9 for XP (or make people upgrade from Debian Stable :).
Third, the reason that design takes a while is because it's hard. I'm really glad that Dave Herman and I haven't iterated the ES6 module design in shipping versions of a browser -- that's not the right thing for anyone.
Finally, you mention Scheme. If you want to see a truly disastrous example of language progress held up by politics, check out the last 5 years of Scheme standardization.
OTOH adding typed arrays or binary data to JS is narrowly targeted and pays off for higher-level API builders. And the typed arrays and binary data specs are being standardized.