Keeping the heads separate allow both for customisable posing and for new head variants that will work with any of the gawnt squads for your army. They come in 3 poses ( neutral, head up and head down ). Some gawnts work better with certain head angles.
So apart from the gigeresque gawnts I have added some of a more alien flavour.
Please leave me a comment for any other head designs you would like to use with your gawnts. The heads are and will remain free, so you can mix and match as desired.