And since they´re planned and drafted to be the cherry pie on top of the sugared ice cream, it´s about the timespan most players need to reach the point when they´ll be able to steamroll the map with anything. Which is past mid game. Midgame is when you´re busily expanding your empire and have tons of different things to do.
CKHO´s are simply a choice. Do you really want to be those troops as you imagine them or not? If not, you don´t need to use them. I have never done so because all I´d like I can get from Pendor Foot Knights and Ebony Gauntlets.
It´s a choice, a decision. If you can´t spare the time it takes and needs or hesitate to leave companions of training them, just don´t use the suckers. Stick with the existing orders, they´re pretty awesome as well, and totally suitable to crush, kill and maim anything you may encounter.
But beating the living crap out of the 3 Seers, Malitse, Eyegrim or an Heretic Army with 200 customized Housecarls of the PlayerCharactersFancy is quite a unique and satisfying feeling. And hopefully reward enough for the long period it takes to upgrade them. The longer you yearn, the better the reward. Or annoying, whatever the experience.
Just like achievements. They matter little. But they´re awesome to achieve.