As I remember it, “coh online” had really cool bulletin drops as one used the units. Or the units got permanently stronger. Such a great game that was.
Defs not permanently in coh2, i think bulletins should be promoting something that improves the quality of play yet not 'spammable' at the same time. So the only way you achieve this is by implementing trade-offs.
Say, you have a bulletin that increases the durability of unit 'X' but only if it comes at the cost of weapon/ability reload/cooldown rate. This brings more depth and uniqueness to someone's gameplay by making the player face the consequence of want such a boost.