Dragging multiple assets to inspector

FWIW, in case somebody else stumbles across this question as I did, here's the solution I have settled on for now. In the script containing an array property, add a bit of code to create a contextual menu, like this:

 [ContextMenu ("Sort Frames by Name")]
 void DoSortFrames() {
     System.Array.Sort(frames, (a,b) => a.name.CompareTo(b.name));
     Debug.Log(gameObject.name + ".frames have been sorted alphabetically.");
 }

In this example, I have a "public Sprite[] frames" property; just change all occurrences of "frames" to whatever your own array property is, and it ought to work. (Also, this is C#; changes would be needed for JavaScript.)

This lets the designer decide when they want to sort, by right-clicking the script and choosing the new "Sort" command the above code adds to the contextual menu.

I don't know if this is still useful for anybody, but I had the same "problem" and fixed it by sorting the Texture2D-array at Start().

 // Texture array
     public Texture2D[] m_textures;
 // 0-based starting position of numbers in image name
     public int m_numStart;
 // Length of the number part the image name
 public int m_numLength;

 private void Start ()
 {

     sortTexturesByNumber(m_textures, m_numStart, m_numLength);

}

 private Texture2D[] sortTexturesByNumber(Texture2D[] f_textures, int f_index, int f_length)
 {
     for (int i = 1; i < f_textures.Length; i++)
     {
         int j = i;
         while (j > 0)
         {
             string l_nameOne = f_textures[j - 1].name.Substring(f_index, f_length);
             string l_nameTwo = f_textures[j].name.Substring(f_index, f_length);
             if (int.Parse(l_nameOne) > int.Parse(l_nameTwo))
             {
                 Texture2D l_temp = f_textures[j - 1];
                 f_textures[j - 1] = f_textures[j];
                 f_textures[j] = l_temp;
                 j--;
             }
             else
             {
                 break;
             }
         }
     }
     return f_textures;
 }

So if your images have names like "image####.png", m_numStart = 5 and m_numLength = 4.