Using the option “Lock Object Modes” in the 3d viewport is useful in some cases but it becomes rather unintuitive when attempting to select a different object via the outliner while in a mode that the selected object doesn’t have (for example, clicking on a mesh object while in pose mode with an armature), as nothing will happen. This means you have to manually turn the feature off and back on again whenever you happen to switch objects. This does not seem necessary for the outliner since you are unlikely to be mis-clicking on things here.
I think it would be useful to have an additional option in the user preferences to ignore the “Lock Object Modes” option specifically for the outliner.