There's no problem at all having translation on the root bone. Many people like to use a "hip" or similar bone to move their character around, so they don't animate the root bone. The reason for that is so you can have some bones, such as IK targets, that are children of the root and don't move around with your character. If you don't need those, then you can use the root bone to move your character around and that reduces your bone count by one bone. Even if you need the root bone to not be animated, translating it in setup mode doesn't have any drawbacks.
