My Shadow has both levels of Codebreaker, and I have yet to actually USE it in a game.
I can see a way it could come up often enough to deserve taking up two slots in the tree: Lockpicking. Plenty of doors in the Star Wars universe are electronically locked, and electronic locks require a code to open, so there's a practical use for the ability. However, as it's written, a rules lawyer could argue that it's ONLY use is Cryptography, and that's certainly not worth two spots on the tree, 25 total points, and being a prerequisite to advancing two paths.