The first thing that comes to mind to me is that someone might be trying to test the limits as to when certain entities are willing to accept unconfirmed transactions.
Thanks a lot for your guesswork. Not really sure for what could this be useful anyway.
Seeing if you could get away with somehow scamming them.
Although in theory 1 unconfirmed is the same as 50, if you have a way of just screwing with 1 unconfirmed input in the chain you have to do something to that one to make the entire transaction invalid.
If there are 50 then and you can screw with a bunch of them your odds are that much better of doing it.
Other than that I have no idea.
-Dave