Big cav units don't spread damage very efficiently. It might be nice to see 3k hits for ego but that unit would have retreated from half that damage.
...And that's a bad thing? I mean, hypothetically speaking it's better to overkill something than underkill it, yes? And also, making some unit retreat at 1500 hits is a materially worse result than wiping it out to the last man at 3000 hits. Sure, sometimes you get unlucky and charge a unit of 20 dudes resulting in massive overkill, but outside of sieges I would take a large cavalry unit over any other kind. I've seen them make the difference in far too many battles to dismiss them out of hand the way you are.
