I disagree with this, changing wheels over is very, very quick and no hassle. I have same size cassette on each set and never need to adjust the hydro brakes when swapping.
I'm sure it's a very individual thing. I'm not very quick when it comes to taking wheels in or out plus I usually end up oily!!!
I'm not organised enough to change wheels ahead of when I need to ride. Along with my midweek buddies we usually decide the evening before a ride where we're going. I've no power in my garage so couldn't swap wheels till the morning.
I'd just end up late and hassled so I see it as a needless chore.
One major benefit to using a dual purpose tyre is the ride can easily mix different surfaces. Like today after 65 miles of tarmac we went our separate ways and I jumped on to the towpath for five traffic free miles to home.