Yes, LOTRO has made considerably more money after going FtP. I'm a lifetime VIP ($200 at launch), and they've also treated us well, to boot. We get 500 "Turbine Points" for free every month, access to all original launch content and a bunch of other in-game benefits. We do still have to buy the expansions when they come out, but that's fine by me. My son also plays, and I've not begrudged spending a couple bucks here and there to grant him access to additional content and features. Considering his short attention span when it comes to gaming, LOTRO has certainly earned its money (he bounces back and forth between Xbox, LOTRO and Starcraft 2... and soon he'll be throwing Diablo 3 into the mix).
For some games (read: bad games) though, it is a death knell. I've been dabbling with DC Universe Online, which went free earlier this month, and I don't see it lasting very long unless they do something innovative with it. It's fun to fly around (or superspeed), and the writing is fairly well done, but it's still stupidly buggy almost a year after launch, and there've been various other issues since it switched to FtP.
I haven't tried Champions yet, and found City of Heroes to be a lacklustre throwback to EverQuest style gameplay. There's still a ton of other games out there, and I'll surely try them eventually just because. I am looking forward to The Old Republic, though. Hopefully it'll be good, and worth my $15 a month.