Why doesnt it fit into it? It was commonly used in combat, especially in the eastern front and in the pacific theater. And since the EF mod has units that have no weapons it just makes sense to atleast give those the ability to use entrenching tools, bayonetes, daggers, whatever they have to fight with.
Melee would bog down combat? I dunno, seeing riflemen standing two feet appart firing at eachother and NOT hitting anything bogs down combat to me