No. Taking out "in the world" tones it down, in the same way that taking the spikes out of a club tones it down. "Why would anyone..." is still a rhetorical question asserting that anyone who does is a dolt. You do the same in another comment: "Why would anyone make a lifetime commitment?" Clearly, many people do get engaged, do get married, do make lifetime commitments. A majority of people, even, at least here in the West; I do not know how it is in Slovenia. (The disadvantageous tax regime you have in Slovenia was done away with long ago in the UK: married couples can elect to be taxed as separate individuals.) But saying "Why would anyone do such a thing" does not invite discussion, it shuts it off. If you actually wanted to know people's reasons, you would actually ask them, and listen to the answers.

It's better. I would say that "I'm surprised that you're planning on [X], considering [list of drawbacks]" would work at least as well. I was surprised at Alicorn (who's generally a calm poster) saying that she was allowed to want things. It seemed weirdly out of line with the discussion. When I saw the beginning of the thread again, "why in the world" jumped out at me as aggressive. Something that's showing more clearly to me on another reread is that you genuinely didn't see what you might have done that was problematic. I'm wondering if there's something odd going on at your end-- I don't think you usually misread things the way you misread Alicorn's original request.