I think that advances in modern lenses may have something to do with that in part due to modern design, and modern coatings. It's true that an older uncoated lens has a certain creamy 'look; often sought after. An example would be Hasselblad C and CFi lenses. Similar design, coatings were very different. The older 'C' lenses are sharp, but how they handle contrast is different to the highly corrected CFi lenses. 'C' glass has a certain look and it's eveident. Most modern lenses are designed with minimal abberations and distortion often inherrent in most older glass, that eliminates the lens character giving it a sometimes harsh and contrasty often referred to as a 'clinical' look. Again, to Ian's point, lighting, film type, development, and printing all have an accumulative effect on how 'clinical' an image looks, and that will be different depending on the glass used. It's a choice the photographer makes and how their personal vision is interpreted, and one of the reasons some older lenses are considered 'legendary' for a certain trait they exhibit that often cannot be replicated in modern glass. YMMV, my .02 c