After having owned, for 3 years now, my 210WBS; I can honestly say that I will probably never own another RV without at least one slide.
There are many folks (I'm one) that will tell you that any type RVing is not "camping". Camping, in my mind, is backpacking into wilderness areas having nothing with you except what you are carrying on your back. Been there, got the T-shirt to prove it.
If you are staying in an RV, you, really, are taking a wheeled apartment or hotel room with you. Bed is a mattress, not the ground, you have to go outside to look at the stars, you can cook with more than one pot at a time when making dinner and your toilet isn't likely to give you poison ivy! No matter what level of RV "extras" you have, any RV is a Hilton to a backpacker.
On those rainy, windy days when the choices are slim on anything but staying indoors, that extra 18" x ~6' of floor space sure is nice! It truly is amazing how nice it is to spend an entire evening in the TT and never have to say "Excuse me, but, can you move a little so that I can get by?" or "your hind end is blocking the TV, could you shift a bit?"; you get the idea. Traveling with 3 cats makes the additional space all the more enjoyable
mechanical and I'm not about to tell you they won't / don't break. They will, they do. Now that they (slides) have been around for a while, they are one of the more reliable pieces of hardware on your TT. You are much more likely to have a problem with the oven, water heater or microwave than you will the slide.
Do they leak? 99.9% of the time - no. Anything with a gasket will leak if you don't take care of it or take precautions. Keep the slide surfaces clean, clean and lubricate the slide seals occasionally and don't park so that the slide is on the "high side" (you're inviting water incursion if the slide roof slopes down into the TT
). I've followed the above "rules" and never had a leak. Others may tell you that they have had leaks from day-one... No answer there...but, if you keep them clean, level your trailer so that the slide is down a half bubble (good idea anyway for draining your tanks and A/C runoff...), I suspect you won't have any leaks either. Of course, with "age" the seals will need to be replaced, but, good care will make sure they last a good long time, mine are 3+ years old and still look and function as new. Lots of people ask about, or go ahead and do it, storing their TT with the slide out. Don't know why, unless they are trying to impress the neighbors. If you aren't using the slide (TT is in storage), store it with the slide in. The slide's wiper seals are just as susceptible (more so really) than the tires, roof and caulking to sun damage and weathering.
All the slides I've ever dealt with have been 12 volt units; i.e., they run off your battery regardless of whether you are plugged in or not. If plugged in, they still run off the battery as the converter is supplying the 12v. If boondocking, the slide still operates off the battery.
Can you RV without a slide? You bet. Lots of RVs still being made without them. You will however, start finding it harder and harder to find one without a slide and if you do, resale or trade-in will be lower (usually) because the demand for the slide is only increasing. It used to be unusual to find a single slide. Now, it is increasing rare to find only one slide...the trend is to "multiple" slides. When we bought our 210WBS, we were actually looking at fiberglass TT (Casita to be exact). We saw the 210WBS and immediately fell in love with the slide. The two trailers were virtually the same length, towed with the same footprint and had pretty much the same amenities, but, when parked and the slide was out on the 210WBS, it "seemed" twice the size of the Casita. I'm not "knocking" the Casita; a truly marvelous piece of engineering and design with a build to match, but... My signature shows what we deemed the most "livable" for us.
Yes, you can RV without a slide. I, however, won't.