Can we get these things turned off on a per-user basis?

Obviously you didn't read the root post very well. The third sentence answers your question by saying:

If this annoys you, please visit Node Display Settings and disable it there.

As for the problem it solves, well many people surf on small screens, and use the code wrapping support that PM provides, while this makes simple reading of the code perfectly acceptable it makes cut and pasting the code problematic. Obviously you dont have this problem, but please try to remember that we deal with users on all kind of devices, operating systems and browsers and we try to do stuff that makes most of them happy. IOW: The site isn't here just for your benefit. (Case in point obviously you don't browse the site on lynx)

On that note, most of the respondants I've heard from like the feature, and apparently the ones that don't found the link in the root node without difficulty and turned it off.