Why now, and not 15 years ago when their reputation started tanking for this reason? And when are they going to ban the re-use of listings for unrelated products?

Agreed. Doing something about this should have been well over a decade ago, not now. Considering how long it took, this isn't going to bring me back from ordering from Amazon.

Their reputation actually dropped for many more reasons.

Prime was one reason - I always hated it and I felt that when Prime came out, the general service elsewhere declined. I could not accept to be a second class citizen now. Either I'd have to also use Prime - or stop using Amazon. I opted for the latter.

But there were also more complaints that people made online, which was different before Prime. The opinion of others does influence me a little bit; I try to not let it influence me, but truthfully when there are many negative comments, one becomes suspicious too. Perhaps one reason Google disabled downvotes on videos, as this was a quality control step by some users, which helped a bit; I would not waste my time on horrible videos. And for the most part, users voting was working ok-ish.