I think you raise some interesting points Thomas. I aslo think perhaps it's hard to comment without really trying to make images with these older lenses & techniques.
Last year I sold a large TP shutter to a photographer for her Darlot lens, I was stunned by the quality of her wet plate work. Back in the early summer I saw some more work by a different photographer at Dimbola House on the Isle of Wight. If the images had beeen shot with modern lenses the character of the work would have been very different.
I hadn't intended to buy a Darlot/Petzval lens myself however a chance encounter with one at a flea market last month and it's very low cost (£20/$32) means I will in fact give one a try. The lens turned out to be optically perfect despite the grime and spiders living inside
It's important to find the appropriate use for these lenses to make work that stands up on its own without looking gimicky, that's going to be the challenge.