Should I require users to register to use my app?

Question

So I'm very close to releasing an app I've been working on, and the server I integrate with allows me to register users. So I was wondering if I should require users to register with the app before they use it. The app wouldn't "need" the registration for any of the features (although I have some ideas about future updates where the user's data could be saved to their account in the cloud), but it would still be nice to have a list of registered users.

One reason I think I should require users to register is because when the app launches for the first time, the user must accept my privacy policy and terms of use; so if I made a registration screen, it might be an easier and more straightforward, rather than bombarding the user with the thick legal language.

But I'm afraid requiring the user to register will cost me some users. I once downloaded an app, and it wanted me to register, but I was lazy never did. Is that a legitimate fear with requiring registration?

Thanks!

Edit: To clearify, if I was to require registration, what info should I collect: name, email, password? other? And we wouldn't be spamming them with emails at all. We also have a very strong privacy policy and would store all data securely.