A lot of people think the same. The parks would be "safer" if everyone who was eligible was required to be fully vaccinated before visiting the parks. I, personally, feel this would have been a better solution and technically safer than only limiting those to in-state (vaccinated or not) if the goal is to limit the spread of COVID-19. At least out-of-state vs in-state becomes a moot point after June 15th.
I was surprised that the mask mandate ends on June 15th along with capacity issues. I'll be curious to see if abruptly stopping both of those has any impact on numbers or if enough people are vaccinated to hold steady. I'm sure
Disneyland will be keeping the mask requirement and health/safety checks for the foreseeable future, though.