Well ... I am certainly not the most experienced shooter on this forum nor the most discerning nor have I done any testing ... doesn't interest me. But I shoot virtually all older, bargain lenses in varying states of decline. If I limited myself to pristine, new lenses, I'd have only 5 or 6 ... this way I can afford to try all kinds of lenses.
If I have an actual chip in the glass, I color the chipped area with a black Sharpie pen ... but the normal wear-and-tear scratches I don't even worry about ... and, as far as I can see, in normal shooting, the blemishes simply don't make any difference. Heck, if you read the literature, they used to claim that bubbles (and the lens makers used the plural) in the glass were a sign of quality.
To me it comes down to what you are confident shooting ... if a pristine lens makes you more confident in your shooting ... by all means, use pristine lenses ... if the state of the glass is not an issue for you ... shoot it, learn its signature or style and use it if you like it ... if you don't like it, you haven't got that much invested. [By the way, the photos you have posted, made with your damaged lens, are gorgeous.]
Here's a link to a page that has often been posted on this subject that is both amazing and informative (certainly NOT micro-scratches, though): LINK