The only concerns I can see are:
1. Opening the slide into something because you weren't thinking when you parked. Like, putting in fuel and oops, need to go, no worries, just jump into the camper put the slide out... straight into Bubba's pride and joy Royal Purple Peterbilt.
2. Someone coming along and clipping the slide while it's out.
3. Forgetting to put the slide back in when you're finished doing your business.
4. Not being able to retract the slide while out on the road. At least when you're at your destination you can drop the camper and leave it there while you seek out a repair. Not so much at a truck stop or on the side of the road.