We do require signing in first, otherwise there's no way to ban abusers from tipping you (if you remember on Stream Donations we never could prevent people from sending you money, only having the ability to block alerts). Signing in takes seconds, and if people do not wish to sign in they can still use Bitcoin.
Since the change to node-webkit last week, issues like this should have been resolved. There's still a few minor bugs, but they shouldn't affect the majority of users. If you're having issues, I'd consider checking to make sure you don't have both the old and new versions installed. When the node-webkit version released last week, it was eventually brought up that the old version remains on the computer. If you have both installed you can just uninstall them both and reinstall the newest version from the website. We also have some debugging instructions available for when you do have issues: http://community.nightdev.com/t/debugging-the-streamtip-alerter-not-the-visual-alerter/1306/1