The locking of dev is done because we don't really want people cheating through the whole thing. We've put alot of time and effort into refining things and testing and revising so that it is fair and the encounters are fun and ballanced. Also, due to alot of changes and tricks we use, the game is even more unstable using dev and it can really ruin a players progress or crash the game. We have a new UI guys from halomaps who is brilliant and really knows his stuff, so hopefully we can get the UI to unlock it for you if you've beat the whole thing on legendary and are warned of the effects when using it. If not we'll just password protect devmode, and give the password out to people that we feel like (not because we like them or just to have there be cool kids) but for people who have a reason for it. Later on like a month or two later we'll probably post the password for anyone who wants to use dev. It's more or less about stability and making sure the work we've done is played the way we want it played, at least for a while.