The balance of the cue is dependent upon the player's style of play.
The balance of the cue should be for how you hold the cue (bridge length and distance from butt of the cue you hold with your gripping hand).
My cues all have a balance point of about 18-19 inches and I have about a 10 inch bridge and I grip the cue about three inches behind the front of the wrap. With that style, the cue feels "evenly balanced" when I am bent over and stroking it.
If you hold the butt of the cue higher than the front, like a lot of players do, the weight shifts forward and a rear-weighted cue doesn't feel as butt heavy.
If you hold the cue at the very butt end and have a 20 inch bridge, like Earl, a rear-weighted cue doesn't feel heavy at all.