To be fair, I don't think it really all boils down to the development crew in NXT being bigger draws than the TNA superstars on an individual level. It's a matter of the WWE being a far more powerful and established brand name than TNA, and thus people being far more inclined to check out a show highlighting people who could be the next big WWE superstars. I mean, according to interviews with RVD and Kurt Angle, many WWE fans aren't even aware that TNA exists lol.