in reply to
When do we change our replies?
I'm not sure if you're asking if you shouldn't post such suggestions at all or if you shouldn't post too much.
I don't see a problem at all.
Suggesting more modern or more perlish code is of course a good thing. Often you can guess from the OP question how much explanation you should add to your suggestions.
The each example would need a hint that it only works for at least 5.12.
If you leave it off and the OP needs the index, then they can ask.
Your suggestions might not solve the original problem, but that's no reason to not post them. Add explanations, or if you have less time, link to a tutorial.
My experience is that some people say "thanks, I didn't know that syntax", a few ignore it, and only rarely there are users who say "don't suggest that just because it's considered modern at the moment".