The visual differences in the examples are quite easy to see. If they aren't apparent immediately to everyone, that doesn't mean they aren't there. The thing is though, flatness can be quite appealing, especially if a person is attuned to the charms of the flattened paint surface, the (2D) space in much modern painting. Reading (understanding) anything, including graphic art can be surprisingly tricky. Our mind and eyes can deceive us. Judging needs to come slowly, usually with much time and experience. With that, I'll leave the world of abstraction, or abstract art ha ha, and proceed to a little descriptive story, flatly told.
I've just sorted and edited over 1000 carefully shot pictures from Big Bend National Park. So, I've lived in, been saturated in a world of images for quite a while lately-too long a while. Anyhow, the images are from old film lenses and brand new designs of all focal lengths (primes and zooms), shot on numerous camera brands. Flatness and the lack thereof really delineates the image style from lens to lens, system to system. It's the main thing that describes a lenses character and the main thing that's seen after hours and hours, days and days of editing. It took this heavy load of editing and arranging slide shows for me to become entirely aware of this. OK. So, my overall impression is that the flatter images coming from the new designs give very consistent results, often stunning results, but also seem to grow wearisome to the eyes at times. The older lenses produce "rather sophisticated" images in comparison but are less consistent, or, I should say, less predictable from image to image. Their images tend to be more challenging to read, harder to deal with in post production. Space is carved up with more intrigue. That's particularly true in this recent outing with the one old sonnar (German-Russian design) in the group, that lens producing some of the most attractive and least sucessful shots. Depending on the shot, all of the lenses excelled of course. So, it comes down to understanding the strengths and weaknesses of each design. I already knew, for instance, that the sonnar design would be a bit dicey with some landscape shots and great for others, but I still put it to the test just to see what I could get away with (I mean what kind of spatially intriguing shot I could get out of the park with...ha ha). I also knew, for instance, that a particular Zeiss wide angle would be relatively automatic in getting "perfect" shots. Using that lens is a piece of cake as they say. The "less flat" lenses I would not want to do without, and, except for the sonnar, are certainly consistent enough. When I go to Big Bend again in May, I'll not shoot the new and extremely expensive auto focus Canon super super wide zoom, nor any Nikon or Tamron or Pentax etc...auto focus lens of any focal length, but rather Takumar and Pentax M primes and a Zeiss wide angle prime. Especially, I look forward to shooting three very old Takumar lenses for their sharpness, transparency and 3D qualities-the 8 element 50 1.4 ST, the old auto Tak 55 1.8 and the 200 3.5 (gorgeous results, super super sharp 4 element design). An old Tessar design Tak macro gets "uniquely flat" images (a macro and Tessar...how could it not?). So, I'll take that lens along (it gets no ca, needs no hood, is good for macro and landscape and won't flare-how conveeeeenient). I'll use the Takumar 20 4.5 (many many elements and the greatest flawed lens I know of) if clouds or rain gets up for the gorgeous colors it produces. I left these old lenses at home for the last shoot, so, now it's their turn. Only when light is harsh will I need an SMC coating to avoid wash out. So, in general, there is merit in using simpler, older designs with less coating for the very reasons stated in the article. That is why so many folks like the simpler, sometimes older designs. But, I'll still get great shots with the new sophisticated Zeiss design and the old macro Tak, even if the images will be "flatter" and simpler. So simple doesn't always get simple, and sometimes sophisticated does get simple, and, in the case of the Tessar Tak, ultra "simple" design (4 elements) does get simple, ha ha. I'm flat out of here!
PS-this list of various lenses...better to be long winded, more specific when a subject has gotten too simple a treatment...proofs in the pudding as they say.