automatic mapping isnt necessary to convert...but in the case of the creature, it's not having you do any extra work with texturing (you're just importing a bumpy green texture)
Automatic mapping makes all of your faces as planar as possible so you dont have overlapping UVs (very bad in texturing). Since the whole model is the exact same texture, you dont have to worry about any other mapping options like planar mapping.

Also, to see exactly what Automatic Mapping is doing for you, open up the UV Texture Editor before doing the automatic map

If you'd like to see planar mapping and how it's done, Simply Maya has a free tutorial on it...i dont have the URL at the moment, but if you do a search for UV Mapping i think you'll find it. or someone else who has the link can post it.

Hope i made sense