As others have noted, the benefit of staying onsite depends on two things:
1) Will you and your party get up and out the door early enough on vacation to get to the park for that early entry?
2) How important are the big-name ILL rides to you?
I'm taking a massive OG SW fan to DHS for MTFBWY. So yeah, we're staying onsite so I can smash my phone at 7:00:00am to get RotR ILL because I will lose my mind if I, the
travel agent and tour director for my friend who has never been to WDW, can't get her on that ride. Totally worth it for us.