Personally I think it's "popularity" (if you can call having marginally more viewers than Stargate: Atlantis "popularity") is due to one of the same factors that contributed largely to TNG's. No competition. With Stargate in hiatus, there are really no other shows of it's genre on right now. I know that's the only reason I watch it.
Well, there's Doctor Who, but the two are so far apart in tone that there is easily room for both without difficulty.
Well, there's that, but between the accents and the characters talking at 6,423,569 words per minute, I have no idea what they're saying half the time.