My feelings exactly Dan. I think a very light, waterproof shell that is only marginally breathable would be quite nice. Windshirts are so light now that bringing both would make a lot of sense. Wear the windshirt to combat wind, bugs and even mild rain. But when the rain overwhelms the windshirt, switch to the not very breathable rain jacket. You could probably do the same thing with a light poncho, but this has isn't as bulky as a poncho.
But if it isn't really rainproof, it is useless for this purpose. I've tried wearing a windshirt in a Sierra downpour and I was glad that I was day hiking. If that was a backpacking trip, I would be in trouble.
In general the marketing on this thing is bizarre. Who hides the fact that a rain jacket has a hood? Are you trying to sell to bikers? Even some of those folks like hoods (when I commuted by bike I preferred to stick my hood inside my helmet). Like a lot of these types of jackets, time will tell if it makes sense or not.