One way to think about it is that your fifth wheel is like a condo on wheels, and you already know all the space and conveniences, as well as the work & costs involved.
But a Class B is like a car - except it comes everything you need to live inside. (Our B actually gets more miles per gallon than our friends' towed car does.)
We use the B for our second vehicle, parked next to our garage so it is obviously a hop-in-and-go scenario. Arriving and departing at campgrounds is almost equally simple, usually just a matter of plugging/unplugging a power cord. (We fill the water tank about every three days, same interval for dump station.)
Not everybody will be happy inside the small space, but to me, the convenience, ease of use, availability of campsites everywhere, and great fuel mileage make the trade-off worth it.
The downside is the cost of even used class Bs, though they do have excellent resale value. We are getting a good return for our money because we use it so much, on the road camping several months each year. If it sat in the driveway, it would be a pricey luxury.