The golf shoe market is easily infiltrated by those who are in the athletic shoe market. They just take a running shoe and put spikes on them. Not literally, but it's not too far off. Over the years many traditional "shoe makers" got in the game, from Johnston & Murphy, Allen Edmonds, Brooks Brothers, and Dexter. Everyone has at one time or another made golf shoes. Certainly you mention a bunch of other brands who have been in/out of the business.
But FootJoy has stayed in the game primarily as a golf shoe manufacturer. They also happen to make dress shoes, but thats not their primary focus. Gof is first, and why they are "The Number One Shoe in Golf."
Your comment is well taken GC - it just SEEMS the competition had increased on a massive scale lately. When one really thinks about it, there may actually be less. Addidas and Nike have been making golf shoes for a while. However, what happened to Reebok? Etonic? Dexter? Johnston & Murphy? When did PUMA get in the game?