I've joined a bunch of public games recently to help coach/encourage the influx of new players, and unsurprisingly there has been a lot of abandonment. From what some of the other players in these games are telling me, the high AFK rate is definitely hurting our player retention: it's hard to strike the right fun/difficulty balance when half the players don't even give orders. And if high-profile free-to-play games have taught us anything, it's that this problem is not going to go away.
We really need a mechanism where players can kick AFKs out of public games. Maybe as a stopgap while the community is still pretty small, certain trusted players could be designated as Admins in any public game they join, so they can sort of moderate the public games to improve the experience of new players? Might be easier than trying to figure out a system that's both fair and effective for auto-kicking.
Might be valuable, but I think this is less important than giving some front-page space to active public games with open positions. If there's one major theme of most of the negative reviews I've seen, it's that premium access comes across as too critical/expensive. Further promoting premium memberships seems like it would exacerbate that perception.