The full members list was disabled by default for Xenforo 1.2. There is an option to display the full members list, but you'll have to take it up with the Head Honchos to see if that's something they would want to have.
What is the downside? I feel like turning it back on is a no brainer, but there has to be a reason it was disabled by default right?
Probably something as simple as either security, or reducing requests on the server. Turning on takes a little tweaking, since there isn't actually a switch, but if it was decided to make it so, I could easily take care of it.
I see no reason to not list everyone. I suppose if there were an option to list active only (say, people who have logged in within 3 months, or the top 200, etc.) then we might have that instead of all. But just 20 seems pointless.
I vote to turn it on. 20's pointless... perhaps a certain post threshold to get on the list... 250? I dunno.
I have enabled the members list. Get a feel for it, talk amongst yourselves. Ask the Big Guys what they think.
marathon's been gone for how long now? Four, five years? And he's still in the top-20 when it comes to post count.