I think the attrition factor is mostly due to rift requiring a much better computer and graphics card than other games, specifically wow. Players try rift and honestly I haven't met anyone with legitimate gripes about the game besides "it wasnt for me" which can and probably does mean anything from "I'm broke and can't afford the monthly subscription, when will it become free to play?" to "my graphics card can't handle rift so I can't raid or be competitive in pvp, even on lowest video settings, so I quit, but I'll pretend I don't like the game, though I really wish I could play"
there was a point several months ago that many hardcore grinders finished the end game content and got bored, some thought pvp was broken, and they only pvp in MMOs, some were waiting for hammerknell, others waiting for ID raid, still others did those raids and felt they had nothing else to do because they only played the game for the top tier content and couldn't enjoy zone events, dungeons, leveling, exploring, puzzles, etc.
rift offers a ton of content but some players only want one thing, like pvp or end game raiding. the most fun I had in rift was enjoying all the different content types.
I don't know if more players are coming back or new players starting now, all I see is the login queue, and low/medium population could mean anything from 500 or 5000 players in a zone. they may have even redefined the "low/medium/high" population values or how many players can be online in a zone at a time to reduce the chance of login queue.
I think the game is great and they're the best MMO, they have a lot of potential and I have no complaints except that some content goes against my religious beliefs, though some principles are in favor of those beliefs. I don't enjoy the hellfire theme, for example, though I do like the angel and faithful guardians. there's many subtle nuances and references to religious undertones and themes, but that's just my preferences and personal taste.
rift is the best game I've ever played.