Select source and target branch on "Create merge request"-View

Why we cannot select a source or target branch from dropdown when creating a merge request as it is possible when editing it?

If you create a new branch and click on the "Create merge request" button, you cannot choose the target branch on the same page. Often I enter information about the merge request before i recognize that the wrong target branch is selected.

So I must discard all inputs or save the merge request and edit it afterwards to change the target branch.

It would be easier if it would be possible to select a source and target branch on the "Create merge request"-View.