Although the portability of the Ooni Karu 12 is a nice feature we planned to keep ours on a stand outside. We live in moderately temperate weather, but we have enough rain and occasional frozen precipitation to which we didn't want to expose our Ooni Karu 12.
The cover does a great job of protecting the oven and looks nice too.
If we need to take advantage of the portability the cover makes it easier to carry as well.