I have never seen anyone else mention this anywhere else, so I thought I might as well.
One of the logical avenues for improving CM, without major reprogramming, would be the addition of more types of terrain. To give a few examples of the current limits; many roads in western europe have hedges/bocage immeadiately to either side of them, creating a very claustrophobic feeling avenue where it would be impossible for vehicles to leave the road. This isn't possible in CM at the moment, the closest you can get hedges/bocage to a road is 10m (You can get the same effect by using the 'road through woods' tile but it doesn't look right and doesn't feel the same). Anyone who's seen the photos of the destruction caused by Wittmann's Tiger at Villers-Bocage will see what I mean, those guys couldn't go ANYWHERE.
You can see another example in any 'continuous' piece of terrain (ie roads, hedges, rail tracks etc). They are limited to four angles: north-south, east-west, NE-SW and NW-SE. This makes for a pretty grid-like map or roads with lots of wiggles. Most roads, especially in north-western europe do not run at right-angles to each other, but go at all sorts of strange angles. I'm not advocating a 'point-to-point' road system (at least not til CM2), but a few extra road tiles wouldn't go amiss.
I can understand that BTS wanted to keep the map design simple by limiting the number of tiles available, but I don't think it would make it too much more complicated to have some extra tiles available; 'Road through Bocage', 'Hedge at edge of cornfields' and roads at that go NNE-SSW for example.
These wouldn't dramatically alter gameplay (except for maybe the bocage one above), but I don't think the gameplay needs improving, it's perfectly fine as it is, they would make the maps feel more natural though, and look a whole lot better.
We're now down to level of turret-tweaks in the patches and I think maybe more attention should now be paid to terrain, and less to the mechanics of combat; terrain is obviously one of the most important factors in warfare.
Anyway... I'll stop whinging now and go and do something useful.
Nick