Bringing this up - does it make sense to do closed gold single dances for standard? It seems like they're underattended.
Interesting question. 'Closed' syllabus in pro-am are really a throw-over from AM. For Am they make sense since you have to master basic technique before trying open. For pro-am they make less so because one partner is already (or often at least) a master of open (actually they really make more sense since it forces the pro to stick to training steps for the am and not run off into the open jungle before they have been learned). What makes things complicated is that most of the best multidance events are, as you point out, open so you feel as if you have to do the latter to be 'in the competition'. Its not true of course (as discussed elsewhere) at least in teh dancesport events where you can win with just syllabus steps (with good judges).
THere is a bigger question - whether there is any point in doing single dances at all. I mean their main function is really to get more entry fees for the competition and the pros - if they were so essential the AMs would have to do them too (and obviously we do not). However, I think they are very useful on a personal level even if uncontested. When you reach championship in AM you have to hit the floor running - your first heat is your first round of the big event. The great thing about single dances is you get a chance to burn some energy, get grounded on the floor and even make a few mistakes before hitting the multidance events. I think AMS would kill for that.