Am I missing something or is was it a conscious decision to remove that feature in this interface?
It's still possible, but hidden.
We currently don't have an explicit entry point for this, but you can paste an image link when the uploader UX is showing.
We will be updating the experience to add an explicit link to upload via URL. That is coming soon.
However, this is still an issue with touch devices as reported on How to insert image by link using touch devices?.
There's currently no way to do that directly, which is the biggest problem with the "invisible" paste target.
Right now your best workaround is to download the image with a browser and then upload it via the file picker.
Fortunately we have a design tweak in the works that will make this possible again.