David Barnett
"A large part of Krenov's fame came from his passion for teaching. A large part of that passion necessarily involves encouraging others to build similar works and continue to push that trend of design in new ways using new ideas."

And I said:

"Krenov is a special case inasmuch as he promoted his designs and working methods as part of his teaching and writing, sharing his style and the means to imitate it with real generosity of spirit."

I'd also add that Krenov guided and encouraged students to explore his design vocabulary and was happy to promote his students work, which in spite of many innovative features, are still often quite derivative, as one would expect. Nothing wrong with that.

"At what point does "inspired" become "copied"?"

When it's hard to find anything significantly novel in the ensuing version. When it's obvious. Don't forget, there are many artists, craftpersons, designers and performers who copy their own work, their earlier successes, often tiresomely. Sometimes they move on, sometimes not. But at least in these cases, they were originators of their signature style or their individual expression of a broader style.

"And, one more time, why is it considered ok to copy old stuff, presumably anonymous, and not acceptable to copy newer works?"

Again, when its origins and chronology are obvious, at least to those not entirely ignorant of the original work or designer's oeuvre and place in the history and development of design. Copying another's design, something not perhaps as easily or yet widely recognizable as another's design, to represent as one's own is theft, plain and simple, and no rationalizing will make it otherwise. The fact that is too often done is shameful.

[added] Of course, once a design's been around long enough, you can claim it as your own and if no one exposes you or challenges you, you got away with it, which to me doesn't make it right. That there's no longer legality at issue wouldn't change a thing for me. Even if you were to hire lawyers and legally make someone else's recent design your protected property, that's still theft in my book and in spite of a legal appropriation of another's original work, it is immoral. "Just because the cat had her kittens in the oven, that don't make 'em biscuits."

"How many modern designers have come up with something that looks a lot like a Barcelona chair? Or a Parson's table?"

Too many. And I would make a distinction between first designers and those also described as designers as second designers.. We apparently have or use only one word to describe different classes of designers. We could draw distinctions between designers who really created something with little or no predecessors, and those that modernizeor update a design, perhaps making it easier to produce, giving it a new look, making it more accessible through economies of manufacture, and so on.

I'd say that covering a parson's table in galuchat departs from the original parson's table to the extent that it shows, or once showed during the Art Deco, a novel way of presenting that established design. No one of even only moderate sophistication will fail to recognize that parson's table's modernist beginnings, mistake it for anything but a parson's table, but will see the galuchat re-expression of it for what it is, regarding the novel material as making us appreciate the interplay of its original simplicity and minimalist lines from a textural reinterpretation.

In the following decade, that parson's table will be covered in parchment or vellum to fit within another design context. So I'd regard this as design, but design at a lower rung on the hierarchical ladder.

A copy of a Barcelona chair is simply that, a copy of a Barcelona chair. If you wish to regard the new 'designer' as a designer of the first caliber, that's your right, but I wouldn't likely grace the subsequent with any comparison to the former. If one sees the new chair as a Barcelona chair, then I'd say it's a copy of a Barcelona chair. If it sits like a Barcelona chair, is built like a Barcelona chair, and you'd call it a Barcelna chair, then only those elements that depart from a Barcelona chair can be considered for their design value, and if those elements do not offer enough novelty to make you not see it as a Barcelona chair, then it's a Barcelona chair and not an original one.

That's how I see it, anyway. There's lots of room for argument, drawing distinctions both subtle and gross, which has long fueled this part of the design debate. Fun, no?