You've summed up my opinion pretty well. Cedar Point has one of the best coaster collections on the planet, but Kings Island is the better park in almost every other way. KI has the better atmosphere, better/more courteous staff, and is a more well-rounded park with a great selection of attractions both for thrill seekers, and for families with small children. Admittedly, KI is my home park, so I may not be able to be completely objective.
Cedar Point is great when it's great, but their management, staffing, maintenance, and operations seem to be less consistent. Anecdotally, last year my very best park visit and my very worst park visit were both at the point. CP also has to contend with the problem that they may actually be too popular for their own good, and they have had trouble adequately staffing the park for the past few seasons, especially during the early and late season. Unfortunately, this means that the park is understaffed during HalloWeekends, which can be some of the busiest days of the year. As you can imagine, an exceptionally busy park that is seriously understaffed leads to a greatly diminished guest experience.
I also think that some enthusiasts, and especially folks who lived in Ohio in the 1990s and early 2000s (myself included) tend to hold Cedar Point to a higher standard than most other parks because we remember how amazing it was during that time. It's still a great park, but in certain ways it isn't what it used to be, and so we nitpick.