But in doing that, you are basically infantilising one half of the transaction. In this context, I find this rather objectionable. If an adult has sex with a minor, quite rightly, it is the adult who is breaking the law, but not the child. This law treats women in the same way as the law about the age of consent treats children. It does the opposite of the New Zealand approach - it disempowers the women involved.
It is ludicrous, imo, unless you treat the women involved as helpless victims, which is unbelievably patronising. But as that judgement Random quoted above shows, the law in Sweden isn't quite treating the women involved as helpless victims - it's actually being used as a stick with which to beat immigrants.
I didn't have particularly strong feelings about this either way before I started looking into it. Now, I do - I think this is nasty stuff that ought to be vigorously opposed.