No offense taken, MickB. But, I believe the base malt in the Johnnie Walker blends is Cardhu. If it were Laphroaig, the peat and medicinal notes would be much more prominent.
I, too, in general prefer single malts to blends, but do enjoy blends--particularly JW Black--on occasion. The single malts you mention are excellent, each in their own way. Yet, sometimes I want something a bit more mellow yet still flavorful. Single malts by their nature are intensely flavorful, but are often one or two dimensional. A blend can offer a more rounded, multi-dimensional, less intense taste experience. Single malts are not necessarily better than blends; they're just different.
If someone gave me the choice of JWBlack or the single malts you mention, I most likely would choose one of the malts. But, if all he had to offer was a dram of JWBlack, I would happily accept.