We’ve been Disney’s Hilton Head Island numerous times and Disney’s Vero Beach once. We always have a great time. One of the HHI trips was in the dead of winter and it was freezing and rained the whole time. It was still great and had plenty of activities for the kids. We didn’t even get to the beach except for one short nature walk.
All to say, the WDW resorts are great vacation destinations in their own right. They have activities going on for kids during the day, along with pools, etc. If the parks are closed, they will likely have more activities on schedule (think scavenger hunts, etc.).
I say go!! It will be a much cheaper vacation without the parks, too. Sad, yes. But doesn’t need to be an either, or. Just different. We plan to go to the Boardwalk area, which we’ve yet to explore. And maybe see the new Cirque du Soleil show that just opened. Fingers crossed it stays open!