Poor choice of words on my part. I didn't mean structural issues in a construction sense. It doesn't look like the slides are going to start crumbling soon.
When VB opened, it had a lot of TapuTapu issues, some crowd control issues, and some other more general issues. Those issues can't be fixed by just refurbing rides. If Universal wanted to make drastic changes to the park, a long park closure (like at the Disney water parks) would give them the time to make those changes.