But when you quote a post it fills all that stuff in for you, and if you manually type the quote tag, you're usually not going to type a PID and dateline, most users don't know how to get that information (especially the dateline), you'll just type a username, if that. If it was this:
Yeah, the syntax is much clearer, but it won't necessarily make it much easier for people to use as they're not going to put a PID or dateline in anyway. I don't think there's been any people (not loads anyway) saying they or their users don't understand the quote tag.
Saying that, the other features added by Yumi's quote tag plugin are cool, but if it's just a matter of changing the syntax, for most people it's not going to make much difference as they usually only use the standard [quote] tag on it's own if they type it manually.