I responded to this question on Quora, and my answer received 5,300 views and 59 upvotes!
Here's what I said.
It’s easy to visit the Netherlands without speaking Dutch. Living here is a bit different. Yes, most people speak English so you can get around. But there are some notable exceptions.
-- You will be functionally illiterate, especially in the beginning. You won’t be able to read your bills, official government documents (immigration papers, drivers license info, immunization notices, etc.), menus, the push/pull sign on doors, etc. My apartment came with a bunch of cleaning products and it took me a full hour to translate all the instructions (the brands were completely different from what I knew). Kind of a pain when you just want to clean the bathroom.
-- If you have young children, they won’t be able to talk with their local peers -- because kids don’t learn English in school until they are around 10. Likewise, it’s hard to find kid’s activities in English or children’s movies that aren’t dubbed in Dutch (whereas movies for grown-ups are kept in their original language with Dutch subtitles).
-- Some people don’t speak English or don’t speak it well. Like my elderly neighbor who really wants to talk about our shared gate. Or the tailor two streets down. A bus driver. The woman who runs the ice cream stand. It’s overly simplistic to say that everyone speaks English here.
-- And by not speaking the local language, you miss out on ease dropping and chitchat. Sounds silly? Perhaps. But if the waiter cracks a joke and you’re the only one not laughing, or if there’s a big news event that has everyone chatting in line at the vegetable market, or that bus driver wants to talk about the weather -- you’re going to miss out. And it can feel very isolating.
That said, I’m glad my boys are forced to learn some Dutch. And as a resident, I’m trying my best to learn, too. Why wouldn't I try to learn the language of the country I’m living in? The Dutch make it very easy for English speakers to live here, but it’s helpful to learn some of their language too.