You're going to get a fuzzy file finder, Git integration, syntax highlighting, symbol navigation, and and a package manager immediately available to you in those editors. None of those are available in Vim by default; that's the inspiration for Amp.

There are additional perks to including things by default, too. Jump mode is a good example of that: it's integrated with its select mode. You can start a selection and then switch to jump mode to move the cursor to complete the selection.

Lastly, there's simplicity in including things rather than asking new users to pick from a dizzying array of plug-in options. Rails is a good example of this: there's a lot of functionality that could have been left to 3rd-party gems, but having the framework include them by default means they'll work out of the box, and there's a single canonical solution to [sessions, templates, ORM, routing, etc].