I've met Robert and seen him live (he played through my jbl equipped twin reverb at a show back in the late 70's). Great guy, great lyricist. I recall him writing complete songs for himself, but only providing lyrics for Jerry and the dead.
As to the dead 'clones'... tribute bands are fine, but I'm pretty sure I don't want to be in one. The influence though, is pretty unavoidable. Lot's of folks missed out on the real thing and want it (some nights I like to reminisce as well). I see the boys trying lot's of things over time to carry the dead forward. That it doesn't measure up to some's standards because Jerry is gone is a pretty short issue... nothing you can do about it. I do see them trying their best to continue and replicate what was, but also pushing things with what skills and people and ideas they have. Dissing anyone as being a 'Jerry clone' is pretty weak. They have to maintain an audience and build on what they've accomplished. (and yes, I've seen nearly a hundred shows with Jerry).