Corgano:
I see your point.. but the combat spell is pre-existing when it enters into the background count. The spell starts at the caster... forms it's own astral construct which then flies to the target.
Isn't that only the case when it comes to indirect combat spells? If I remember correctly, direct combat spells (like power bolt) create the spells effect at or within the target, which is why transparent barriers (like a window) between the mage and the target have no effect when it comes to direct combat spells.
If you need a fluff reason why...
Nope, not really. I am mostly interested in how the rules are officially intended. And since the only passage in the rules that goes into this specific situation mentions that all spells are affected, it seems to me that the rules intend to weaken both sustained and instant spells.
In regard to the "abuse" of Astral Hazing: You and Mithlas make it sound as if this quality makes a character significantly more powerful, when in reality that isn't the case. None of the characters abilities (social, matrix, combat, etc...) receive any buff from it. All it does is to protect a character against one specific kind of attacks: Magical attacks. He remains just a vulnerable to social attacks, matrix attacks, poisons, disease, bullets, grenades, etc.... as anybody else.
And while such a BGC is certainly an advantage for a character who is likely to be attacked by magic and unlikely to be supported by magic, this is not the most common situation for runners. Most runners probably have at least one mage in their team and stand to profit from spells like invisibility, levitation, healing, mask, increase attribute, etc.... And at the same time they will only occasionally run into enemy mages. So essentially he loses some significant magical advanatage all the time, while only occasionally receiving some benefit against enemy mages.