I don't think that's what's happening at all.
People are interested in genealogy. Maybe not everyone, but a lot of people. People are even more interested when said genealogy connects themselves to someone who is a historical figure, and even more so when connecting famous people to historical figures. I mean, really, there's a franchise of TV shows dedicated to showing the genealogy of various celebrities.
I highly doubt most of the genealogists who look into the ancestry of the commoners people who have married into royal families start out with the intention of finding their royal ancestors. More likely, what they're doing is researching the family in general, not specifically looking for any royal connections. If you're able to go back far enough though you're going to hit nobility and/or royalty at some point.[/QUOTE
I do because it is almost becomes a selling point by palace PR when a major royal is newly engaged. The 3rd sentence in your 1st paragraph is exactly my point. I enjoy genealogy but I think people sometimes make more out of a connection than they should, that's all. If Maxima and Silvia are descended from Inca emporors from the 1200's, it's an interesting fact and nothing else. Just as you stated in your last sentence, "if you're able to go back far enough, you're going to hit nobility and / or royalty at some point."