why do we care so much?

[semanuelp]

I think it depends on the type of photography you want to do.
Each type of work requires quality and suitable material.
In the case of "Street Photography" anything goes. In this case it's not, of course, the optical quality that is important but the content of the image. Old lenses will do the job as well newer ones.

 

[TXForester]

This is one of those questions where there isn't a right and wrong that applies to all. What is right, or wrong, is personal. Some lenses are better from a technical stand point. You can make measurements to back that up. However, some lenses are better only because the photographer, or photo viewers, like a distinct quality they lend to the photos.

Then there are differences like fast glass vs. slow glass. If particular situation calls for fast glass and there is no work-around, then you the answer is simple.

But, I think the main point of your post is most lenses today and many from the past are "good enough" for most of us. I agree. There is so much more that goes into a good photo than what the lens brings.