You could get day tickets at Disneyland before EPCOT opened. I still have some that are hand stamped and signed from the late 70's.
The parks are out of control. You pay more for longer wait times. On the other hand if they lowered prices/let more people in, the wait times and crowding would be even worse and there would be complaining about that. The real problem is they just need more parks - some in the midwest wouldn't kill them so people wouldn't have to travel as far. Spread the load out.
It might have just been bias growing up with Disneyland but I much preferred it to the magic kingdom - it seemed like they watered the individual parks down to encourage people to park hop.
The real issue is I think a lot of companies just assumed they couldn't compete at the same level as Disney so they didn't even bother trying. I think Universal with Harry Potter found out that yes, you can steal attendees from the house of mouse and providing a themed experience is also doable - they are far from invulnerable. I'm eagerly looking forward to Universal's Epic Universe; hopefully it will light a fire under others (hey Cedar Fair - there's more to parks than just coasters!) that it is worth it to up their game too.