The original system came out in the very late 90s. I want to say just in time for the millennium celebration. Prior to that, everyone just waited. But unless a ride was super new or Space Mountain the waits were not terrible. Back then you had no fastpass line stopping progress of the stand by line so the lines flowed a little better. I went to MK the first summer Splash Mountain was open and waited well over 2 hours to ride. But Space and Thunder waits weren't bad. Haunted Mansion and Pirates and most everything in Fantasylnd was walk on or less than 10 minute wait. The addition of FP+ has kind of messed up the flow of the line at Haunted Mansion. Same for Pirates but I think that ride also has experienced a surge of interest ever since the success of the first movie. Neither one had FP prior to FP+ and the lines were very reasonable.
That is correct, to a point. SM was a long wait and at rope drop there was a literal stampede from the gate to SM. It was the epic ride at the time. However, I never waited over 40 minutes for any ride previous to that. I never waited that long at SM either because I just went to others and later in the day, the line at SM was manageable. You did wait in lines, not as long as you do now without a FP, but, the point was that the line kept moving all the time. You didn't stand there in the heat and watch a grouping of people legally cut in line in front of you. It was way less frustrating. We all were equal. No one got ahead of you. When you were next... you were next, no debate.
When FP first came out it did have a 1 hour window to use, and that never changed. It was that they stopped enforcing it. If you got a FP you were able to use it whenever you felt like it. That screwed up everything until they had to change it back to enforced 1 hour windows. That was their own fault. If they had just enforced it from the beginning, it never would have gotten out of control like that.
I like the current FP+. I almost never plan far ahead, in fact, last February, I managed to use my phone to make FP+ selections for Epcot (and then two more later the next day for MK) the night before I went. I find it so much better to get the FP's I like in my ticket and not have to run all over the park to gather the others. It is worlds better. However, that said, having been a yearly visitor for years before FP, I would love to see the whole program burnt and thrown away. The attitudes, the anger and the frustration just wasn't there before FP... it is now a major part of the Disney experience. Kind of takes the fun out of it in order to cater to the Type A personalities that have to rush through everything.