Here's why it would be a major benefit:
- Enhanced possibility to communicate with individuals from around the globe
- Better chances for English-speaking people finding jobs in Sweden
- Making Sweden more foreigner-friendly
- Improving connections of international relations
- A greater opportunity for foreigners to learn and study the English language
Immigrants from English-speaking countries who do not speak the language are generally at a serious economic disadvantage. It's much more difficult to get and hold a job or find a place to live. If a vast majority (90%) of Sweden's population speaks satisfying to outstanding English, then why make it hard for English-speakers to find a job or live in Sweden?
Especially the Scots-Irish Nordic-sounding brand of northern English (England) and Scots (which is what originally English came from, unRomanized). It's the Italians, Spanish, French, Irish, Germans and even southern English that are at a serious disadvantage if they don't know English or any of the Nordic languages. So I think this question isn't needed.