You can already do all of your examples. URLs are autolinked, bullet points just require \n\n, and there's a 4-space prefix for preformatted text.
I think extraneous formatting would just create more incentives to write long, pretentious, streams of consciousness comments where someone just screams from their soap box instead of actually engaging anyone.
I think extraneous formatting would just create more incentives to write long, pretentious, streams of consciousness comments where someone just screams from their soap box instead of actually engaging anyone.