@Goofyernmost , you are getting at a good point that I like. At least I think you are. Every attraction has based itself on something that appeals to audiences. In a non-legal sense, every attraction is based on an IP. Mission Space takes advantage of people's curiosity and interest in space and Mars. And in the end, I wonder, what's more popular? Guardians of the Galaxy, or space? I think an even stronger argument could be made for yetis vs Avatar. Or dragons, unicorns, dinosaurs... anything vs. Avatar. What's more popular? What would be a bigger draw?
There are certain ones like Frozen and Star Wars where the IP is so strong that a comparison like that couldn't be made. But much of the time, I don't think the movie IP is any stronger than, for lack of better wording, a more generic idea.
But I think the real difference is that back then, Disney often ensured that the "IP" fit that part of the park. Location was the prime factor, then IP. So for example, they'd think "oh, we want to add a new ride in Frontierland. Lets come up with what we could do." And then Thunder or Splash Mountain was the result. Location came first.
Now, the IP has taken such a priority that it often comes before location. For example, they wanted to have a Frozen ride. Then they thought, where should we put it? Or they want a GotG ride. Recently they thought, where should we put it? The IP comes first.
And alas, I suppose that wouldn't be such a problem if they actually did choose the best location for said IP. But recently, that hasn't always been the case.
I could provide some exceptions to both of those, but to me, that seems to be the trend and a key difference between then and now.