How about before we start asking for new features we list some essential features from all the series, things we have used that we have liked that maybe got canned the further the series progressed or got changed but would like to see again or just some essential features that you would hate to be lost:
-Bring back unit descriptions. A small paragraph of what the unit is about, what weapons contains and an example on how to use it would be nice, specially for novice players. I saw this feature present in CC2 and CC3. Example from CC2 when you select a sherman tank:
"The Sherman is the most versatile tank in the Allied arsenal. The M4A1 has a 75-mm main gun and two .30-caliber machine guns. Use it to destroy light and medium tanks, infantry, and enemy strongholds."
-Change the level bar designator for attributes for more easy reading. Since CC4 the bar is just one solid color with out delimiting the possible levels available for easy reading. How experienced is that guy? is that morale bar at half or less? in CC2 and CC3 you could easily tell the level of experience and morale at least. In CC5 a fantastic mod called rank-mod was made so you could very easy tell the level of the ranks of your men and the level of their attributes by adding a number for each level at the top of the bar of the attributes and in the upper corner of the rank graphic.
-Keep an introduction video or at least a text detailing your objectives and what is expected from you. Maybe the whole actual history of the operation you're playing can be made available apart on the cd or install application for further reading. The best with out a doubt was CC2 with its daily video briefings on how things progressed in reality so you could see how good or bad you were doing, also that amazingly well done interactive manual/history and game encyclopedia. In CC3 you were given briefings on the objectives and sometimes the overall picture at the start of the operations and on every map, like what unit you were attached to, your supposed location etc. Not all of us are experts in history nor experts in weapons. I didn't even know about the Mortain offensive before PitF.
-Allow for more variety of soldier designations, not just the usual commander, leader, asst. leader, gunner, loader, crew etc. This was done in CCM and CCMT. Likewise separate between sides so you can have a Commander, Kommandant, Komandir.
-Sharing teams between two battlegroups that occupy a single map. A feature from LSA.
-Easy drop and use custom maps. In cc3 you could just download a map and put it on your maps folder to make custom scenarios in it.
Add to the list!