Yeah, requiring a login is one of the things I'd like to eventually do away with but it's not high on the priority list as it's a fair bit of work for not a lot of gain to most users, especially those who pay for a subscription.
The app is very much built on the premise that you setup your "Pool" before you do anything else (volume, type, etc). We chose to require a login so that we wouldn't steer users down a possible path of setting things up on one device, then not logging in to "sync" them, and repeating this on some other device(s) where they could end up in a state of conflict across devices if and when they wanted to start sync'ing their info. So instead we said, let's always sync the info, even if you don't pay for the app, so that at least the information is consistent no matter where you login from, and avoid more potential for headaches with data duplicates/conflicts.
As with anything, it's entirely possible to achieve the app not requiring login with enough effort. However, I think most paying subscribers (who we will always need to be logged into the app) would rather see feature work that benefits them more directly.