`griddata` expects `xi` to be of shape `(M, D)`. My intention was to allow 1D `xi` of shape `(D, )` as well. And I don't see how in that case `_ndim_coords_from_arrays` helps.

What exactly is the problem with `atleast_2d`? Is it better to drop support for 1D `xi` in favor of the solution used in `griddata`?