[popo]

Oh, specifically on colour, I don't buy it that modern lenses are somehow lacking there. It is a basic part of physics that at every interface you can get reflection, but modern coatings significantly reduce those. What about glass colouring the image? Again that can be controlled through coatings acting as a filter. At worst, you get some light loss overall. While not all might like to, there is a lot you can do in post colour wise.

Hmm... if I get really bored some time, I could put up a test here. Take as far as is possible the exact same shot with some 50mm lenses and we can have a game of spot the difference.
Sigma 50mm f/1.4 Art - representing a modern design with 13 elements in 8 groups.
Zeiss 50 makro - At 8 elements it doesn't come close to the Sigma. Is this modern or not? The Canon version was only introduced in 2010, but the Nikon version was around before that in 2006. But had they used the same optical formula before then?
Canon FD 50mm f/1.2 (not L). This is mount converted to EF, and as long as I focus close the mirror doesn't try to get intimate with the lens. This has 7 elements and as far as I can find this is the new FD lens introduced in 1980. I think we can safely say this is an old design.