[Insert John Goodman meme here]
Am I the only one here who actually likes the long upgrade time?
From a game design standpoint I think it functions very well. In the games I've played it serves as a nice incentive to play through that mid-late game slog where you're too strong to be defeated but not yet strong enough to go on a map-wiping rampage. If I had my CKO's significantly earlier the game would be a foregone conclusion and the endgame would be just a simple grind, and I doubt the game would hold my interest enough to play through to the very end. As it is it's a nice end-game reward and once I have them fully upgraded they come in at just the right time to make the end-game mop-up much easier.