Here is the famous Walt Disney quote about
Disneyland being a family-friendly destination:
“The idea for Disneyland came about when my daughters were very young and Saturday was always Daddy’s day with the two daughters. So we’d start out and try to go someplace, you know, different things, and I’d take them to the merry-go-round and I took them different places and as I’d sit while they rode the merry-go-round and did all these things- sit on a bench, you know, eating peanuts- I felt that there should be something built where the parents and the children could have fun together. So that’s how Disneyland started. Well, it took many years… it was a period of maybe fifteen years developing. I started with many ideas, threw them away, started all over again. And eventually it evolved into what you see today at Disneyland. But it all started from a daddy with two daughters wondering where he could take them where he could have a little fun with them, too.”
Note it doesn't say anything about the park being "affordable to all" or "reasonably priced" (which is about as subjective a measure as you can get.) I'd challenge you to find a quote which implies that Walt ever believed the park should be financially accessible to all. Even before these price increases--or any other increases over the past 50+ years--there are millions of people in the US and billions around the world who cannot afford a Disney theme park vacation amongst their other necessary living expenses.
Walt was a businessman. He certainly strove to deliver a better park than the carnivals and amusement parks which were standard in his time, but he knew he'd have to charge accordingly.