My answer depends on when you are going. For right now, sure. Obviously no reason to stay on site.
but it’s not over. Changes are still coming. Disney has millions of aulani and riviera points they are trying to sell, and giant luxury hotels like Jambo and contemporary they are trying to fill. Big announcements are still coming with genie and with APs, and all of this is connected.
This. We're still in in a pandemic situation with things in flux. I have no doubt Disney will incentivize on-site stays when demand dictates it. They don't even have all hotels open yet...that's first priority. Once they get on-site back up to full speed and the post-pandemic travel bump wanes, I have complete confidence they will find ways to make sure staying on-site is attractive.
People's comments here are correct; currently there are very little special incentives to on-site vs. off-site and I don't blame many for dipping their toes off-site. We have always split our stays as even at the height of on-site benefits, we found the economics not worth it to commit to 100% on-site costs.