Those are good points! Tradeoffs.
When I use my hitch box, I do have to move the license plate (and I got tamper-resistant bolts on everything, so I have to pull out the Special Screwdriver set), and the resulting car length is such that I can't comfortably load in the garage (it all fits, but there's no room to swing it open, so I can't open the Ascent hatch unless I load in the driveway).
It does block the backup camera, but I have a Touring with the camera mirror, so I can see behind... but it looks out rather than down, so not an identical replacement for the backup cam view.
One more, mounting it on the hitch is a one person job (tilt up, rest 2" mount on the lip, lift up, and push in). But removing it is a 2-person job so I don't drop it on my foot. The rooftop Thule is light and can be a 1 person job.
But it sure is nice to have all that deep and wide space, just cavernous. And I don't need to step up on anything to load/unload. And the height of the car is unaffected so I can go into parking garages without worry (Thule rooftop box puts me at 8'2"). Each does a slightly different job.
With both boxes mounted, there is lots of room left in the car!
F.S.