Do what, parse JavaScript into plain text? You're right, anyone can do that if they really want to take the time. But for whatever reason spammers don't bother going that far.
I'm no fan of security by obscurity, but let's be pragmatic: people will get less spam if Google fixes this problem.
This can easily be fixed, and should be right away. If Google is turning JavaScript into text output, they can easily parse that output (just like the spammers currently are) and see if the text contains an e-mail address. And if it does, they should omit it from search results (unless the address was originally plain text and not obfuscated, in which case they can assume the author wants it searchable).
"Engineering without management is art." -- Jeff Johnson