Like Gaffer, I would have laughed if Jango's head had fallen out. So I definitely don't think it would have helped the film (though it couldn't have made it any worse, the film is already superlatively awful). I also think it would have added more to the identity crisis the prequels seemed to have, fart jokes galore, then a man get chopped in half, frolicking in flowers and riding giant ticks, then killing an entire village of people including the women and children, and one films later the main protagonist slays a bunch of innocent children who look up to him and think he has come to save them.

I don't think we need to add a small child dumping his father's severed head out of a helmet to the mix. The idea of a kid holding his dad's severed head is kind of disturbing enough; the idea of that scene was that he was holding his father's helmet (I always assumed the head fell out during the rolling) and staring into it forshaddowing that he would take up his father's mantel and become a bounty hunter like his father.

EDIT: Wow, I had never heard of that Death Troopers book, I don't really keep up with the EU much. The overly gory (by SW terms) cover caught my attention, so I went to read about it, and it actually sounds really interesting. I haven't read an SW EU novel since the 90s, but I think I might check this one out. It sounds like the kind of EU I always liked best, takes place in the SW universe, but has nothing to do with any of the main characters or situations from the film (I loved the Tales from Mos Eisley one-shot comic book for that exact reason).