while I understand the pve may have elements that do not fit the vision of the campaign, I don't see why the campaign shouldn't have the option to access many of the content available to us in the Pve.

Fundamental stuff like new enemies (biovore, tzaangore enlightened etc) would absolutely improve the single player experience. 

I would also love to see more arsenal from pve in the campaign as well, and perhaps we should also have access to some wweapon customisation, such as cosmetics and perks. The weapons in the campaign are essentially Grey weapons, yes, but I think some weapon perks that can modify weapon behaviors (new combo, attacks etc) should be a part of the campaign. 

Perhaps there should be a higher difficulty setting in the campaign as well that would allow the use of relic weapons, such that we can play the campaign with the same difficulty of the pve operations? Or a non codex applicant mode where we can use every weapon and also have some modification to said weapons? 

The campaign is very fun still, but to see it get basically no changes since release is just unfortunate. Plus, single player mods aren't white listed either so if we have campaign mods we won't be able to play ops with others unless you reset the game which is just a hassle.