Talked with the team this morning about this - after raising the issue a few times via Slack, email, and our weekly reports.
Basically, there is an internal roadmap for the Armory to release new items, refresh/re-feature previous items, and to bring in more Vehicle Dressing items. Over the next few weeks you should see some changes in the Armory to reflect this, such as new soldier skins, vehicle dressings, etc. I've also confirmed that there will be some BOINS-only dressings (such as Epic and Legendary), but there will be quite a few that are CC/BOINS (meaning you can use Company Coin OR BOINS to purchase the items).
One of the limitations with the Armory is the amount of items that can be put there - there's limited real estate in the Armory UI so they have to make decisions based on various factors - which include cost (BOINS or CC, or both), player acquisition rates (how popular was X last time it was featured?), etc.