In my opinion do to the wood used when building some woods almost always should be cored for stability. Birdseye Maple is such a wood just as an example, now coring Birdseye will depend upon the grain and figure. If the wood is just sick with figure and eye's the grain will be very wavy and it can fracture in some cases with little abuse. I have seen a number cues over the year's break just below joint from simply being drop and hitting the ground at angle that caused the shaft and but to flex. In some cases I have seen the bottom of the pin was exposed in others they split much farther down the forearm.
However, in all cases I am speaking about there were no impact marks and the wood fractured along the non-straight grain. I suspect that not coring when dealing with certain types of wood like I have outlined is like playing Russian Roulette, you never no when the chamber is loaded or when you are going to have a dry fire.
On a personal note I only core when I am concerned about these factors, however, when something is cored all stress within the wood is relieved and that section should never warp, and by coring with certain woods it is easier to make the cue hit more repeatable. Also like you said above coring a cue will allow for weight control, and pin point balance of a cue, but there are others methods that can also be used effectively. So some cue makers core all their cues, some core certain types of wood, and some will not core anything, I suspect that it is personal preference and the amount risk you are willing to take.
JIMO