You could be right - that the children died of other causes. After closely screening the pics available though (not Hajj's of course) - there is no evidence to show that the event itself was staged.
1) The children appear to be in a state of rigor mortis. This occurs shortly after death and doesn't last very long.
2) We do not have photos of all the victims (and the Red Cross did not order autopsies) - so it's difficult to assess trauma damage. If the children were caught in a collapse some would have died via suffocation (dust and debris) and some from head trauma (common in small children) and some from other, more visible traumas. So far, the visuals are quite similar to victims of building collapses during earthquakes.
3) We have absolutely no way of knowing what caused the building collapse (bomb from above, explosion from below or within, structural damage???). Damages and trauma are different depending on the collapse origin and direction.
4) The International media seem little interested in the truth. They are looking for the "shocking" headlines to grab their audiences. In this race for ratings the means to reach the truth is now permanently buried.
5) The theory that the bodies were planted is not one I would be willing at this point to entertain. It simply raises more questions than can be answered (ie: rigor mortis = recent death; difficult to plant bodies deeply underneath existing rubble; too many non-hizbullah personnel involved in rescue efforts; some of the people buried in the building actually survived).
The fact that it is being discussed and analysed, though, is a good sign. Shows that some people still believe the truth matters. As an Israeli on the receiving end of Hizbullah's daily madness - that's good to know.