What would you change in Heroes of Might and Magic IV?

...and generally remake everything to be like the third game – and it would be a complete blast!
Actually, these are two different games, each good in its own way, and there's no need to force one to conform to the rules of the other – it's better to play each according to its own rules. And it's perfectly possible to enjoy playing – you just need to adapt to a different tactic.