Before I had an awning attach I would always climb topside to sweep off the slide out before retracting if we were parked under trees...with my awning that is not an issue anymore.
Next is something I have not had to deal with so had never thought about it before. An RV service dept guy told me he recommends slide out awnings in the event of camping in the snow. A layer of snow with freezing temps and you won’t be able to retract your slide out. I can’t imagine needing to climb topside onto a slippery roof in freezing temps to scrape/chip snow and ice off the top of the slide out...can’t be at all beneficial to the top of the slide out exterior.