Not everyone uses JavaScript, and as a user is prefer basic HTML websites over JavaScript bloat every day. Also note from the article, that the conclusion seem to be that Google does in fact index JavaScript content, but only for trusted websites. I very much like this decision, because JavaScript (and Ajax in particular) is so easy to abuse, and it's never a win for anybody when you're redirected to a bloated website that downloads 100s of MB over 100s of requests and from multiple domains. Also, they're a billion dollar company, I'm sure they've already A/B tested enough to decide that indexing JavaScript is not good :)
