Though I've never seen or played it, I think there's a couple factors at work:
1) When Seminole is at it's best, most northern courses are closed, and the weather at southern transition zone courses can be poor. So it has little competition among "winter" clubs.
2) It profits from it's place as a Ross course that hasn't been screwed with too much. Much like Pinehurst No. 2.
3) That Ben Hogan chose to practice there ahead of the Masters will never hurt your stature.
4) With most Florida courses being relatively flat with abundant ponds and palm trees and wall to wall bermuda, Seminole is probably downright "hilly" and "linksy" comparitively. That it is likely so much better than most Florida courses might set it apart.
Here's a pretty sweet video that I believe was posted in another thread awhile back regarding the C&C restoration:
https://vimeo.com/185644621