Florian this time I have to disagree with you when you say
Might as well have been printed just in offset.
As for me, on the other hand, I beg to differ because I find nothing artistic at all about such reproductions of paintings on stamps printed in offset as the one in http://goscf.com/t/65636#571751
The offset stamp you mention there is Austria Scott 727, a detail
of Klimt's famous painting Der Kuss
Here are two of my scans of the stamp, mint on left, used on right
and a cropped section taken from the painting I found on line.
The scan of the mint is not good, too bright, sorry to say.
When I compare the stamp with the actual painting it is quite
a good likeness and that is what I want see when stamps attempt
to portray a painting,or watercolour or whatever work of Art.
For a 1964 multicolour offset
printing done by the BrŁder Rosenbaum
it was actually a good effort compared to what was printed offset
at that timeby other printers/countries.
I don't want some artistic interpretation by either the stamp designer
or the engraver or the printer.