Oh, I totally agree it looks so much better without a top box, and it stays off when not needed. Stability problems at speed are probable (and warned about in the documentation), but for touring with my SO on the back I'm not doing "at speed" anyway. Cruising at, say, 120kph the box won't be an issue, unless I fill it with lead or something (max 5kg, they say).
I think it looks borderline ridiculous, tbh, like a Lamborghini pickup truck or perhaps a Zonda with a trailer, but I want to go for the occasional long trip on my daily ride, so the RS gets boxes.
(one YouTube reviewer said he couldn't imagine anyone using the RS in the rain, even - he'd get a heart attack seeing my bike fully loaded, I'm sure, haha)