There is a good reason for new features. But it might be nice if those features came as part of an official set of extensions around a stable core, to get the best of both worlds.
Not necessarily. They're all features that currently exist in the core product, making that product larger and more error prone. Thus, the support story is either the same, or smaller if one of those features isn't activated.
Having them run as extensions doesn't mean that there's a public extension API, you can keep that interface all to yourself. It means that from the developer's perspective, there's a core offering that the most senior members can handle, but the smaller features are both bundled, and can be more easily passed to other teams.
It's the same idea behind using libraries, instead of shoving all the code into one place. But it forces you to have a single structured interface to extend the product, instead of touching every other file when you want to add something.