Scandinavian and Dutch people are not ashamed of their languages! Why on earth would any nation be ashamed of their language? No offence, but that is a bizarre idea.
In fact, the Netherlands, Sweden, Denmark and Norway are all countries whose citizens are proud of their very different cultures, traditions and national identities. In general, the smaller and more minority a language group is, the greater the sense of identity and regional allegiance.
The use of English as a lingua franca is a purely practical matter. English happens to be a world language, and Norwegian is not. Simple as that. The inhabitants of these countries are aware that they need to be proficient in a world language to survive in an international environment.
Swedes and Danes are happy and proud to be exactly what they are, and nobody is suggesting that their ability to speak a world language makes them any less Swedish or any less Danish, and it certainly doesn't make them British. Britain has nothing whatsoever to do with this.
Looking again at your profile, I can only assume that the sub-text of your question is 'Why don't they use Esperanto instead?' Interesting idea. Let's see what the Scandinavians and Dutch have to say about that.