Please research the history of e-tickets and ride ticket books at
Disneyland to understand how tickets were sold during Walt's lifetime. There was no "fair" ride system. You paid an admission fee and then paid per-ride ON TOP of that. The more popular the ride, the more expensive the ticket. For instance an "e-ride" (the most popular rides) ticket was more than 8 times the cost of an "a-ticket" ride. In todays terms, we could say that if it cost you $1 per ticket to go on Triceratop Spin, it would cost you $8.50 to get one ride on FoP. And you could buy as many ride tickets as you would like. So, the number of rides you rode was completely dependent on how much money you shelled out to buy ride coupons. And if you were a member of the Magic Kingdom Club, you had access to discounted tickets. Monetizing FP+ is far more in line with the original Disneyland ticketing system which existed when Walt was alive.
It was far, far less egalitarian than it is today. Unlimited use tickets (like we have today), weren't introduced until the 70's (after Walt's death) due to competition from other theme parks that had introduced the concept in direct competition with Disney. So, Walt never "wanted" an unlimited use ticket system. It was pay as you go and pay, pay, pay for more, more, more. I find it humorous that people on this board attribute these mythical, charitable qualities to Walt Disney. He was a business man and wasn't giving anything away for free!