Given that golf overall isn't incredibly popular and certainly representative of more of a niche sport, it stands to reason that any competitive subset aspect of golf would create even more of a niche following. Golf doesn't appeal to a lot of people, and long drive contests are only going to appeal to a subset of those niche followers.
In all honesty I'm surprised that the long-drive championship has survived over the years, especially considering how the popularity of pro golf in general has waned over the past decade.