Also, beyond all of the reasons mentioned.
I think that you will find that many software programs that updates a database automatically will often require a registration, just because they need to know how many are using the service which helps to know the need for server support etc.
This is probably one reason that SB S&D is having server problems now because they have no idea really how many users are needing their updates since they are the exception to the rule and don't require registration. The are in the process of adding more servers due to user overload which has caused many errors on DB uploads recently.