This software was not made primarily for desktop, it is made in HTML5, to run on browsers. In order to make it run on desktop, we use NW.js to package it, which may cause the file to be about 400 megabytes, since it needs to include the package needed to run an HTML5 app on the desktop.
We've had users in the past asking us to include 32bit versions on our other tools. Maybe you don't need it, but someone else might. I don't see why including a different option would be an issue.
The focus of this tool is to have a way to quickly preview Normals without having to boot-up your game, or even needing a game engine. You can simply drag'n'drop the image and you've got a preview.
For instance, it's useful if you work with pixel art, and are creating Normals for your sprites manually, and you need something to quickly check how they look.
I had no idea what Gnome Keyring was prior to this, our tool is self-contained, it doesn't interact with any other software. But since it's an HTML5 app, it could possibly trigger other apps that have behavior related to the browser.