From the OP:
"2. If one seat opens at a discount fare you can grab it for one passenger using Change Reservation or rebooking."
Perhaps a restatement of this point, but inspired by a current post in this forum: If you have let's say 5 people traveling together on OWs and the fare drops, you can try refaring them one-at-a-time until the system won't allow any more. Might be 1, 2, 3, who knows? Easier than the risk of messing with a RT, IMO.
Then sometimes after a lag (maybe overnight), more seats might open up at the lower price.
For people who book with points for co-travelers who don't fly much, the flow of points back into your account is smooth. A few bucks of TTFs each for people who rarely fly are a pain.