One concern about lithium cells is safety. Shorting alkaline cells won't do much, and even nimhs are relatively benign, but lithiums can start fires or explode when mishandled. Shipping lithum cells is for that reason bit of a hurdle too.
I think that's why the raw cells aren't used as the level of swappable unit very often. If the battery is at all removable, they're often integrated into packs which have some level of built-in protection.