I think a lot (maybe even most) people take the "there are no ranged weapons that function in astral space" line to mean that astral combat is more akin to melee than ranged combat. I take it as a restatement of the "there are no ranged magical weapons, period" concept. (Technically a gun could be magical, but only for pistol-whipping people.) But, naturally, the book is damnably vague. "Astral combat is resolved in the same way as physical combat." Does that simply mean attack roll then defense roll? The rules never mention a soak roll, but I give one anyway. Do combat modifiers apply? Are there charging attacks, interrupt actions, or called shots? "Oh, maybe Street Grimoire will clarify it once it comes out." lol no.
Balance-wise, I like astral combat being ranged because it makes it less niche and guards against some broken scenarios, like the ones Ryo pointed out. From a fluff-perspective, having astral combat be melee would only be practical for projecting magicians. Anyone merely perceiving, and limited to their physical body, would be hopelessly outmatched by a being that can "move almost at the speed of thought." (The astral "walking" rate is 100 meters per Combat Turn.) That would make astral combat completely nonsensical for barghests, hell hounds, ghouls, sasquatches, or anything else that couldn't astrally project. Worthless skills are worthless, so let's go with the interpretation that makes them not worthless.
I'm not sure that interpreting astral combat in this way requires spellcasting to be similarly re-envisioned. They don't use the same attributes nor the same skills so I don't necessarily draw any equivalence between them.