Why bother, indeed.
There are so many issues. The names of the device types don't match the names of the devices as marketed in the US (e.g., Grohe Blue 2.0 vs. Pro).
Adding the device also reconfigures it, so if you have things up and running using the display on the device, it resets whatever you did, losing usage data, etc.
The add wizard the first time has you create a home and room but doesn’t mandate specifying the country. This is a problem because the store option doesn’t work if you don’t specify the country, and you can’t edit it afterward.
After deleting the home to reset it, the old devices get orphaned. In my case, I have five devices that are in an error state and dissociated from the configured home, and they can’t be removed.
Beyond that, the app is essentially useless beyond reading filter age and canister state, but it appears to be unrelated to the data displayed on the device. It’s like someone said, "Have an app," without even considering what it would be used for.
More generally, it has the distinct feeling of a third-party-developed application by people who didn’t even have a device or understand its use cases.