Actually many relatively simple rulesets can give complex results, such as chess for example.
As I said, I dont mind Shermans being as good as Tigers if the game itself is fun. First and foremost I wargame for fun; not to flawlessly recreate historic scenarios.
For every detail you put into a ruleset, their is more messing around with dice and tables and less actual playing. But on the flip side, less detail can equal less strategy. The perfect ruleset should find a happy medium between detail and playability. Of course everyone's idea of that happy medium is different, which is why some wargamers prefer simpler rules and others more complex ones.