…and they haven't mentioned it at all as if it's something they are working on
This is one of the most ridiculous decisions they have made. Call of Duty back in 2007 let you pick between grenade launchers, scopes and silencers, and not suggested whichever one you picked was Gorilla Glued to your gun never to be removed again.
I fear that the introduction of the player ran economy of On Foot Materials on Fleet Carriers will be "good enough" and that people will be fine just engineering weapons from scratch if they dont like the mods they chose.
I find this notion to be unacceptable. At a bare minimum we should be able to overwrite specific mods at the loss of the original mod mats. At best however we should be able to store and swap mods between weapons.
And before you go "you need to post this on the forum", I have and I bump the post periodically.