I'd second this in a big way.
We're an MSP with 11+ techs, who are looking at adding 40+ sites with Instant On. Having centrally managed logon, with the ability for me to enable and disable techs as they come and go, and easily provision a new site so techs can start working on them.
Being limited to 3 admins and no central management- it seems like a big miss. (Or, a big opportunity!)
I'd love to talk to someone at Aruba about how this could be implemented!