When you view an album in the mobile app, you see the release date at the bottom. Not just the year, but the month and day as well.
In the desktop app, even after the March 2021 update, you can only see the year.
For parity between the two apps, the desktop app should show the full date including month and day. Since desktop and web now use pretty much the same layout, this could be implemented for web as well.
The full date is very useful information to me and currently I have to check my phone or use the API to get it. Specifically, my use case is making monthly playlists (I think this is pretty common). However, this is not only for new releases: for example, with older club-oriented electronic music, knowing when songs dropped relative to each other within a year is contextually important.
It's not important to me how the date is displayed, just that I can see it somewhere on all platforms.