I don't think you should consider pieces in isolation. If you go back and play Panzer General - the inspiration for Civ 5's 1upt - you'll notice two things. First, the density of forces is much lower in PG. There's space for flanking, or alternate routes. You need to concentrate your forces instead of a broad front. Second, you aren't actually playing against the AI. The AI is bone stupid, and it's obvious when you switch sides and make it attack you. You're playing against the scenario designer, who set up a tactical situation that the AI can handle - to a certain degree.
These are the two core changes that make Panzer General a classic, and Civ 5's combat forgettable. 1upt is a red herring without the supporting changes that make it a compelling experience.
One of the most important characteristics to me is a consistent scale. Civ 5 drives me crazy in that regard. During the 100 years war, English longbowmen did not support the fighting in France from Dover. Keshiks that had been hoarded for centuries were not critical in breaking the lines in WW1. Modern rifles do not have a shorter range than cross bows.
Hexes are enormous outside combat - taking decades to put a road in, providing enough food for thousands, etc. - but small enough that an 'army' is a single type, and battleships can reach across them. Shoot, the maximum range for an Iowa class battleship is 24 miles! It's this weird mis-mash where isolated pieces make sense, but if you step back it's a lunatic asylum where no two systems agree. That's what I'd like to see fixed.