The article takes me back to back to college getting that Psych degree. It was depressing. The book "Blink" by Malcolm Gladwell is an interesting read related to why we do what we do (and how little we think before doing it). I'm with Krusty, it would be a turnoff to start seeing a bunch of gimmicks instead of, say, the Beaufighter.
A 3 week trial is good. I think the more you play this game the better it gets (to a point) and that point is well after the 2 week period. What about a special? $60 for a 1 yr sub? Its win-win. 1. The new gamer saves a bunch of money and his exposure to the game is likely increased. 2. I obviously haven't done a market analysis but I'd bet HTC keeps a higher portion of "nibblers," more than offsetting the reduced cost.
When I've joined it was because of #1 WW2 aircraft!!

#2 The unique challenge of flying against real people. #3 Supporting something that attempts to preserve the WWII aviation experience in a fashion.
When I've left it was because: #1 Spending money after interest ran out IE: No larger strategy in the game. I don't need to level up, but let someone WIN! #2 Feeling obligated to play a video game to "get your money's worth" doesn't feel healthy- kneejerk reaction is nix the sub.
Other ideas:
1. Be nice to a newb. Don't thump your chest at someone with a .021 K/D. We all know we're men with chest hair and cajones the size of mature grapefruit.
2. Auto-assign newbs to an "Aces High class" (AH MM DD) which will serve as an initial squad. The class as a whole will be assigned a trainer. Even if training is skipped, just talking to noob peers will help the learning curve and avoid the embarrassment of "alt-F4." There is a bond formed in the shared vulnerability of the unknown. Seeing "JoNewb landed 2 victories in a Ki-61 of AH0608" will serve as notice that someone new is learning the ropes. Also, seeing "You shot down JoeNewb of AH0608" might stop you from said chest thump because you know there's no reason for it.
3. Let us see career stats from the clipboard, not just tour stats. Continuity is something. "Building the back of a baseball card" is fun.
4. Only charge the card for months we actually play. Poor business practice? Market analysis needed. But I will say that any logical person who hasn't played an hour's worth of AH in the last month is hearing an unpleasant flushing noise coming from his wallet that he won't want to hear again.
5. Slowly decreasing subscription costs for long-term players. Actually, by the time you've hit the 10 year mark on this game you should probably be getting a timecard in the mail...
6. Work the history element. Jane's WWII fighters did a good job integrating historical material into the experience. Each plane had a bio and there was access to ace interviews (always praising the fighter in question). When you flew an aircraft in that game it wasn't a flight model, it was history.