And then there's that picture I posted above of a slide unequivocally stressing the need for rehydration, from a presentation by Lallemand just a month or so ago.
Denny, I think you hit it on the head when you said they don't recommend rehydration *for homebrewers. * There may be good reasons for professionals to do it. But on the homebrew scale, taking into account the atom bomb/hand grenade analogy, the risks (contamination, damage through improper procedure, etc.) probably outweigh the benefits. However much good yeast ends up in the wort, it will, like a vitality starter, take off quickly and be sufficient. I don't think it is merely trying not to intimidate homebrewers with elaborate procedures, but that their requirements really are different.