Well I see this situation on a totaly different way. The thing is "argentinian women prefer or tend to look for foreigners men" (we could make an exception with spanish or italian men, since they are pretty similar to latinamerican men) because in a super general point of view latinamerican men TEND to be kinda agressive, possesive or raw, almost like the "latin macho steryotipe" that a lot of people have in mind when you think about latin men (and you aren't latin). So in contrast, foreigners men seem more soft, gentle, kind or sensitive. Again, this is just a super general point of view of a young argentinian.
And there's another reason too, the physical and cultural (language) impact factor. It means basically, when you have a life meeting the same kind of people, you could get bored easily of what you get (and see)! Then you meet with a foreigner and you think (wow he/she is exotic and interesting).
This phenomenon happen in the whole world, not only here.
And OF COURSE there exist bad people who just want to use you for status or papers, as you say, but I don't think it's the only reason.