(As someone who has lived in different countries) Making an effort to learn "enough" of a language of the country you expect to be living in for a while is a gesture of decency. I feel that good will is justified, especially in cultures that see a lot of immigration and tourism. People try to live in a coherent society, which becomes hard if a large group of people is incapable of communicating naturally and reasonably fluently. Most Western European and Northern European people speak excellent English, but it's not nice to force a large group of people to switch to English and hamper natural communication style because somebody is slightly disrespectful and lazy.

You can get away with a lot in Dutch and especially Flemish Dutch though, because the local dialects are so strong (for being a relatively small area). Unless you look exotic, people don't always immediately pick you out as a non-native speaker.