Ah, I get it.
You want to add a key even if you didn't change the value.
You currently use CTRL+L while you have a bone selected, so you add a key for its scale, rotation and position.
Hmm.
I guess I have some tips for now while the feature is absent and don't know how to best implement it yet.
If you already keyed it previously, you can select the bone (which focuses the dopesheet on just the bone transform properties, its child slot color keys and mesh deform keys). Then use CTRL+SHIFT+L to key the currently present dopesheet items.
Again, this only works if those items were already keyed to begin with. But at least you'll only have to manually do it once.
ALT+ARROW KEYS also navigates/traverses the tree.
So ALT+DOWN selects the tree item immediately below the current one you selected. If the bone is expanded in the tree, the slot you want is probably the one right below it.
Lastly, using CTRL+L can result in a lot of unused keys.
Whenever it makes sense for you, make sure you select your animation and use the "Clean Up" button below the tree to remove unused keys. This will help keep your dopesheet a bit tidier (by only having the keys that are actually animated.) Fewer keys also means animations will be lighter to calculate in-game, which means performance gains if you spawn a lot of that skeleton.
