Because they are the names of the Princes?
That wouldn't be my first association. I would think that they are both average, kind of common and boring names, typically paired together.
William is a filler mn somewhat and
Harry is just an average name. I don't see how it is really too much. There are a tonne of kids named
Charles William,
William Charles,
Henry William (
Henry is
Prince Harry's full name),
Charles Philip,
Philip William,
William Henry,
Harry William,
Elizabeth Mary,
Diana Elizabeth,
Elizabeth Anne,
Elizabeth Victoria,
Victoria Elizabeth etc etc
The royal family are all named common and timeless names, so it is only natural that they will be used a lot.
Sorry just had to voice that! To me the royal connotation isn't too much, it just turns me off it! I hate names I associate with the royal family and steer clear of them as much as possible. Die-hard republican here :)