If I understand this correctly you could take this skill but do everything a Rogue can do but not be able to disable Magical Traps?
Is that correct?
Correct. As a note, everyone can find magic traps with Perception now -- a change from 3.5. And after that point, there are ways to deal with magic traps other than Disable Device.
Off the top of my head, if you want a Rogue's Disable Device, then you can take one of the Bard archetypes, or the Ring of Maniacal Devices. Both APG.
from what I can see you are correct, disable traps and mechanical locks. And depending on the class skills you get a rogue might have an edge on most other characters.