You're right that Disney's Fastpass system is included with park admission, but I wouldn't say it's "at no extra cost." Keep in mind, a one day ticket to a single Disney park (no parkhopper) is $80.00 plus tax. The cost to build, stock, and upkeep those Fastpass distribution machines is factored in there. The problem with a system like that at Kings Island is, the price for a daily ticket would need to be high every single day to manage that system, but the system itself would only be used on Saturdays in the summer and Haunt nights, so someone visiting on a Wednesday in May would need to pay more for their ticket, then have access to a system they didn't need.
I also suggest that, if you truly only visit once every two years, you come here to ask for help planning for the trip. There are only a few days during the years that any of Kings Island's rides approach a wait time that I would call "hours." If you really only have one visit every two years and you choose a Saturday in July, you've dug your own grave. I would say on an average day in the summer, the longest line you'll find is Firehawk at 45 minutes to an hour, while everything else will be between a walk on and 30 minutes. On most days, you can do the entire park in a day.
Also as you've read here, many make the case that this world affords more to people who will pay more. People often bring up an interesting argument: If it is indeed immoral for someone to pay extra to have "no wait," then is it immoral for you to come to Kings Island at all, since there are people who can't afford it? Is it wrong that there is a tiering system in place there? There's no right or wrong answer, and I understand your frustration. But on another level, the worst thing you can teach your kids is that life is fair. They needn't know the whole story, of course, but you can say "Those are the people with big houses and lots of money." It's something they probably already know as reality, or will learn soon.