for various reasons.
In regards to the Swiss Guards, they were originally mercenaries hired by the Vatican sometime in the Middle Ages, and it just became a tradition. They were well known for their effectiveness when the crap hit the fan.
Swiss banks - I would assume this has to do with taxes and/or their neutrality in wars.
Swiss neutrality - this is because every male citizen (maybe females, too) is required to serve in the military for two years, and afterwards keeps their service rifle; also, I believe they have a plan to have every bridge in the country blown up within 24 hours of an attack.
International organizations - once again, I would simply assume this is a coincidence, due to taxes, regulations, and/or their tradition of neutrality through strength.
So no, IMO, it's not that suspicious at all.