Here are a few valid reasons, from a user's point of view for registration:
1. I want to use your site on different machines.
2. I have no idea when where my cookies go or do, but I know it's good to delete them from time to time.
3. I have information on your site that I consider semi-private.
4. I really like you app, and I like being a part of your community (assuming you have one).
5. I really like the people who use your app. (You've already said this isn't valid in your case)
I wouldn't discount the first three points though.Instead of requiring it, just make it optional and ask why people are signing up during the process. They'll let you know.
1. I want to use your site on different machines.
2. I have no idea when where my cookies go or do, but I know it's good to delete them from time to time.
3. I have information on your site that I consider semi-private.
4. I really like you app, and I like being a part of your community (assuming you have one).
5. I really like the people who use your app. (You've already said this isn't valid in your case)
I wouldn't discount the first three points though.Instead of requiring it, just make it optional and ask why people are signing up during the process. They'll let you know.
Good luck!