If it was an incredible deal or something else really pushed it above the competition, we could live with it but all else being equal, it's a big plus.
Access to the fridge is probably more critical. Stopping at a rest area or gas station, they typically have a bathroom but no fridge means we can't get to the food.
As mentioned, it's usually possible to put the slide out but an extra hassle. Also, what happens if the slide fails and you can't put it out. Being able to live and function with the slides closed while you wait for repair is a nice backup vs having a trip end.
