"the Summer equivalent of Prince Albert of Monaco"? Seriously?
Johannessen may very well be on the way to a European Tour Card, Campos is on the PGA Tour, Yuan (at the moment) on the way to a PGA Tour card, Gavin Green is on the European Tour and Zanotti the same. That's the bottom five at the moment all on (or with chances of reaching) the top 2 tours.
The main issue is that the golf schedule is already packed and the Olympics haven't got the prestige (yet). Plenty of major golfers still feel strongly about participating and some of those who withdrew 5 years ago have made it clear that they regret doing so.
The universality is a major part of the Olympics and one of few things that still show some of the spirit of the first Olympic Games. Making a selection where even decent golfing nations like Denmark and Germany would struggle to qualify (in the men's tournament) would make things so unolympic that even I as a supporter of Olympic golf would say that it should be left out!