That's a puzzle, and I share your concern that more top players haven't signed up for English Turn. Of course, it's scheduling isn't as attractive as it used to be. That notable 1995 tourney that Love won to get into the Masters (Crenshaw's miracle) took place the week before the Masters. And New Orleans, if I'm not mistaken, has been moved around several times. That tends to dampen commitments.
On the positive side, the PGA TV promos for New Orleans are some of the best I've ever seen.
One of these days when I'm healthy, let's play.