They don't like the game enough to pay for it yet they want to play it for free and spend their time in it.
In other words, their time is less valuable than $15/month.
If I hated this game as much as some of these folks and I thought that it wasn't worth the sub, I think it would't not be worth my precious time either and I wouldn't waste any of it hanging around.
For free we get the best content the game offers. The sub 50 content is bar none leaps and bounds above any other MMO out there. That's why the end game is such a let down. It's just nowhere near as fun. So when I say it's not worth it to spend the $15 a month it's because the game lacks in areas that would make me want to spend the $15.