Thanks for submitting the interesting article. I was surprised to read that parents in Europe are wary of bilingualism.
It is TIME-CONSUMING to maintain both languages at a high level, especially if literacy is expected in both languages and the languages are not cognate. We are trying to keep up Mandarin (not a NATIVE language for either parent in our family) and English (my native language) in our family of four children, and our children have plenty of interests that take a lot of time and attention (hacking on the computer, for my oldest), so literacy in Chinese is a struggle here where there is such a sparse supply of reading matter in Chinese. But it does seem worthwhile to make the effort.
An additional point: keeping multiple languages in use is easier for everyone in a family if each language is cued by particular situations, for example speaking to someone else who only knows one language the family knows. And sometimes habits can form patterns of language use even among multilingual people. For example, my wife speaks their joint native language with her two parents. She speaks a different language, the official language of her country of birth, with all five of her siblings. She can speak that language with me or with my children, but tends habitually to speak English (my sole native language and one native language of my children) with us. My children have varied in what language they speak to one another depending on what country they were living in at the time.
I guess its a little more difficult to be multilingual in primarily english speaking countries. But in countries like India (where I'm from) anybody who has gone to school can speak and write at least two languages, in most cases, 3 or more. This is possible because, every state in India has its own language, then there is a national language, and then there is English. So it becomes English + Hindi (national lang) + mother tongue (Tamil, Telugu, Marathi etc).
That said, those languages all have very limited scope, just within India. Not much useful for a career abroad. It does help in becoming a better language learner though.
I don't think parents in Europe are wary of bilingualism per se. I think they are wary of starting both languages at once. Many speak one language to their child until it speaks reasonably, and then start the second language (in pre-K or K years).
There are no right answers - either way, there is a tradeoff. Speaking two languages in the household makes it easier for the child to learn them; on the other hand, it does delay speech. My kid looked so desperate to communicate, I stuck to one language until she was fully verbal, and only started the second language afterwards, making it into a game.
It is TIME-CONSUMING to maintain both languages at a high level, especially if literacy is expected in both languages and the languages are not cognate. We are trying to keep up Mandarin (not a NATIVE language for either parent in our family) and English (my native language) in our family of four children, and our children have plenty of interests that take a lot of time and attention (hacking on the computer, for my oldest), so literacy in Chinese is a struggle here where there is such a sparse supply of reading matter in Chinese. But it does seem worthwhile to make the effort.
An additional point: keeping multiple languages in use is easier for everyone in a family if each language is cued by particular situations, for example speaking to someone else who only knows one language the family knows. And sometimes habits can form patterns of language use even among multilingual people. For example, my wife speaks their joint native language with her two parents. She speaks a different language, the official language of her country of birth, with all five of her siblings. She can speak that language with me or with my children, but tends habitually to speak English (my sole native language and one native language of my children) with us. My children have varied in what language they speak to one another depending on what country they were living in at the time.