As a long time desktop and server user, why do I look at changelogs...

New filesystems and major changes to existing ones (large performance improvements, new features like adding better compression standards which I now know I can use, fixes to long-standing bugs which open new use cases).

New protocols like wireguard when it was new and exciting (still is now that I think of it). When that was mainlined, I knew I had some network rearchitecting to do.

New device drivers like amdgpu when it was massive news. Less so these days since most hardware is well supported, and I don't buy the absolute latest.

New kernel APIs which I can use in my programs — like landlock, when it was merged I knew it was time to improve sandboxing in some of my stuff.

Though LWN and kernel newbies do it best, already linked by others.