I think that Gerry Soejatman did a good job in his blog articles to explain how these pilots could end up heading for Mount Salak, without doing anything unusually stupid or daring. (For those who haven't read them: He based his analysis on photos taken in the cockpit on the first demo flight, where both pilots' flight displays and the paper maps on their clipboards can be seen. And he points out that the main difference between the two flights was a change of runway, from 24 to 06.)
Nevertheless, this accident should never have happened in an aircraft equipped with EGPWS (or TAWS, or T2CAS, or whatever you call it). That's what I'd hope to learn from the CVR: was the TAWS trying to warn them at all?