When the park opened on July 18th, 1955, the basic admission was $1, and the rides were sold separately. The 9 attractions that we free were things like the Main Street Arcade, where you could watch others place coins in the games, and sponsored halls.
In October of 1955, after a very successful summer, Walt and his staff looked into ways to make things run more smoothly, and the ticket books were introduced.
http://www.mousemonthly.com/how-much-did-disneyland-cost-when-it-opened-compared-with-today/
It wasn't until Magic Mountain opened up in Valencia, that Disney looked into creating an "all-exclusive" ticket, first offered as a special ticket to folks like the Magic Kingdom Club, which was designed for local groups to get a discount, to compete with the new player in town, who started the main "unlimited rides" option in Theme Parks. By 1982, Disney dropped tickets all together, after a few years of having both options available.