I dont think its a major problems in a kayak or canoe, id be worrying about it for something that spend its life in the water. The only problem with wide strips its conforming to particular shapes, roundish hulls with full bow and stern generally work quite well. If you think about the old cedar canoes you find wide strips, even wider than what we are talking about now, covered with canvas that id say doesnt compare to a fiberglass skin when it comes to moisture protection, and many are happily around from a long time with just maintenance to the canvas and no moisture problems.
I dont think that structurally there is a problem either, to me the strips we see now got to that dimension simply to be able to bend easily across their wide side to cover the bottom or building patterns and designs rather than a calculated structural consideration.
The only thing i wouldnt do with particular shaped hulls its build from the sheerline down. Cedar canoes usually are planked starting from the keel line up and you find filler strips on the sides where they are less of a problem for the structure but visually they dont look that good, cover them with a canvas and the problem disappear. With fiberglass its not a big deal to have filler strips on the bottom, but you can find yourself having to plane down the edges to fit the curve.
The best for me its starting from the waterline instead: the strips tend to follow a straighter line, so they can be even wider, and slightly playing with the width of the strip permits to reduce the fillers to a non noticeable minimum and less fitting work.
You could use up to a 3" wide strip on the right hull but at a point i suppose that its not necessarily faster than a 2".
If you are for a simple, no pattern, functional hull then wider strips are a good way.

: I have stayed away from these very wide strips, as one of the cornerstones of
: the WEST method derivatives is to use very small pieces of wood to keep
: the tension at the joints small and within the elasticity of the
: epoxy/fiberglass membrane, and at the same time keeping moisture from
: spreading far in case a a damaged membrane (that is where mixing old and
: new boat building methods often fail). But maybe I have been unnecessarily
: strict about this. Have anyone experienced any problems with 1,5"
: strips in this respect?