I've always felt that "sharpness is just sharpness". That said, I only really knew a sharp lens when I first had one made by Carl Zeiss (on Contax 35mm film). I mean, that lens was razor sharp compared to anything I'd ever had before that. And to this day, many of those lenses produce beautiful images by photographers who adapt them and use them on modern digital bodies (I've also recently started using them again on Sony A7R "full format"). Modern DSLRs and full-format mirrorless cameras are the "digital film" I longed for when I was scanning and scanning for hours after relative minutes of shooting (back then, you could spend 10 thousand dollars on a 4MP camera with a scanning back, if I remember right, and that was actually favored by many professionals, who also used special software to help them interpolate upwards for larger prints... (but I digress.) But what really made me fall in love with certain "sharp" lenses was not so much how the sharp areas looked, but actually more how the "unsharp" background appeared (not necessarily "bokeh" in the modern "big, glowing christmas ornament" sense, but rather a soft "painterly look" that I found myself drawn to, often more than the actual subject in the foreground and which often looked quite flattering in event shoots. People in the background were recognizable and looked good, albeit soft. (And at such events, if I'm honest, I rarely even got my subject in sharp focus, but they felt flattered, nonetheless. (And they still do, when I use the same lens on modern digital bodies.) Simply said, the "sharp areas" look nice, normally, from any good lens, but a "great" lens is not just sharper; instead, it renders soft areas more beautifully (and has better color). I think the old lenses, designed by old masters, are more likely to have that quality than many modern lenses, even with "improvements" from the new generation of CAD. In short: Character outperforms sharpness; this is why those who have old lenses with character keep them around, even when they have a lens with a comparable focal length, one that weighs half as much, with an electronic coupling and/or auto-focus. We keep our old lenses, sharp or not, for the "character". (At least some of us do. ;-) )