Why? Disney theme parks are literally the worst case for virus transmission. You have 57,000 people in close proximity to each other, all touching the same surfaces then their face, many of whom are kids who won’t follow distancing guidelines or wear masks. Many of the typical activities are literally shoulder to shoulder. Then they go home to every corner of the country and the world and you do it all over again tomorrow. What is the alternative? Just let people go in there and all get sick? At least at sporting events you’re mostly sitting next to the same 20 people the whole time. At WDW, you’re constantly mixing with tens of thousands of people and all touching the same stuff.
Edit: Just did some back of the envelope math. Right now, about 0.17% of Americans currently have it (active cases, not closed) that we know of. If you randomly selected 400 people, the odds of at least one of the them having it are almost exactly 50/50. If you select 1000 people randomly, the odds are 82%. If you select 10,000 people, the odds are 99.9993%. If you randomly select 57,000 people to enter the Magic Kingdom on a given day, you are guaranteed that one of them has it and more likely about a hundred people have it. (Yes, I know that the population of Disney World is not a random sampling of the US, but this is just for the purposes of estimation).
I am just as excited to go back and have literally been annoying the crap out of my family complaining about our cancelled trip and getting them to promise me that we’ll go as soon as things reopen. I want as much as anyone for the parks to be open. But what’s different today as compared to March 15th? More people have it and we’re no closer to stopping its spread by means other than social distancing. If we reopen things today, we will perfectly resume the exponential growth we were on on March 15th. It’s sad. It’s sucks. But it’s the reality and recognizing it as such will keep people safe.