It's because people want to be unique. Especially in
America, uniqueness and being "special" is really important. This has been shown by various sociology and psychology studies, I'm not just making it up.
I believe that a lot of people choose really wierd and/or made-up and/or unusually spelt names to make their child stand out and be special, which is fine although I don't really get it myself. The irony is that names which were "unique" a few years ago (
Brayden,
Madisyn etc) are actually really popular and common now!
What I don't understand is why people have to use trendy names or
really strange names (some people are into medieval, ancient greek mythology etc. not necessarily trendy but still very unusual) when there are a lot of names which would stand out but are still recognisable and useable. Examples are even some of the names on your list like
Eugene and
Francis, or might include unusual but not overly unusual names like
Montgomery,
Malachi,
Evangeline,
Philippa,
Olive,
Wilhelmina,
Simone,
Quentin,
Verity and loads more.