Be careful with the AI improvement suggestions, nalivayko. Soon it will be impossible to beat the AI at hard difficulty.
Speaking seriously, I believe that AI doesn't always have to make the best choice in a combat situation. Many of the commanders are pretty mediocre (like they were in real life - the true geniuses are rare), so it only makes sense that they sometimes do stupid things, like rallying a wrong unit. I make mistakes all the time playing as Carthage. C'est la guerre.
Of course if somebody like Africanus is in that kind of a situation, the chances are he most likely makes the right choice. But I'd like to see the AI keep making mistakes, based on the commander's abilities, though maybe the case of urban legions is a bit too obvious, as they are such great units that one would expect even the stupidest of commanders to realize it and act accordingly.
In the future, it would be interesting to see the commander ratings have more of an impact on what can and can't be done during a battle. I've always liked wargames that give a bigger role to the characters and abilities of commanders, because even elite troops can suffer defeat if their leaders are incompetent, and sometimes a gifted commander can prevail against all the odds in an impossible situation. Maybe add some characteristics to the generals? Something like that is already in the game, like Hannibal's special cards, Fabius's ability to retreat before battle etc. But having more would be great.
"But here we are in a chamber pot, about to be ****ted upon."
-French General Auguste Ducrot before the Battle of Sedan, September 1870