I believe disneytim is correct about ATIS. Started out free, ended up a C (after losing the Monsanto sponsorship, I think).
One thing about tickets: they gave you a benchmark for how the park ranked its attractions, something more objective than your own likes and dislikes and your own passing observations about passenger numbers.
As for the thrill ride aspect, don't forget that the Bobsleds were by far the most popular ride at DL until POTC. They were the first fully-themed thrill ride and remain popular to this day. Also, there was a national survey (last year?) that showed Space Mountain to be the most popular ride at DL, by a good margin. So, you can hardly blame Disney for seeing fully-themed thrill rides (all the "mountain" rides) as the surest bets for long-lasting crowd pleasers. Even POTC has those waterfalls.