Because they weren't done. Not all change is bad. But for a "mature product," one needs to carefully consider the cost of bloat. Modular/plugin type systems (done well) can be one way to avoid this, since they allow users to select their own feature bundle. But you really need to manage the abstractions and interfaces carefully to not add more friction or user confusion.

The first few weeks after the redesign had a lot of bad things that were fixed because people started raising issues.

It didn't show the last commit message, for example.