MAN777,
I'll stand by my point with the geography - when you have a country with one city much larger than #2 - 4x or more, and that city is already the home to the national flag carrier, is the political and commercial capital, and that city has a significant tourist infrastructure, it almost always follows that aviation activity will gravitate to that city. Whether you want to call it moths to the light, or a self-fulfilling prophecy, this will be the major hub, just as night follows day.
This situation is especially prevalent in the UK and France, but also I would say the same scenario applies in each of the Nordic countries, and in Ireland. I would also say it applies to Mexico, South Korea and Taiwan.
It is not a universal phenomenon, nor does it seem to have any impact on the overall success of a country - as it clearly does not apply to the USA, China, Italy, Spain, India, Canada, Germany (as discussed) or Brazil.
Wherever you have one dominant city, residents in the others will complain about it - but even in countries with several major cities of similar size and importance, you still have regional disparities and rural-urban tensions, it is a fact of life.
Now with respect to Swizterland and the Netherlands, you have two special cases. Zurich isn't the political capital, but the Swiss cantonal system is highly devolved anyway, and Zurich is a major financial centre, aswell as the hub of the national rail network. However, Geneva is both key to the UN (hence NYC being a viable destination), and a major centre for low cost flights serving skiiers. Therefore, ZRH will always be the hub, but there is viability for Geneva in its own way too.
The main population centres of the Netherlands are concentrated in the Ranstad region, which includes AMS, The Hague and Rotterdam, which is just 26 mins away from AMS by fast train. Therefore, AMS is a natural hub for the whole country, not just the (relatively small) population of Amsterdam itself.
If you don't have the conditions above for one city to dominate, then it is anybody's game to become the major hub - hence the evolution of cities in the USA where the airport is indeed built, and they do come.