Because for many users Attachments are essential and it's very uncomfortable to install many plugins.
And it's difficult to keep many plugins up to date.
```Our philosophy for Flarum: provide only the absolutely essential features in core, and offer the rest (such as extensions) via extensions. That way, you can build your custom forum, exactly with all the features that you deem necessary, but nothing more.```
What is about the like system? Is this necessary? 😛