Are you running a stock clutch and cable? Then you could get away without one, but...
I would recommend getting an adjuster, at least in the future, only because the purpose of the stock self adjusting quadrant is to account for stretch and slack in the cable over time.
If I remember correct, the BBK cable is adjustable. Is this right? If so, you don't have to get the fire wall adjuster, you'll just have to crawl under the car to make any adjustments.
Well, ultimately if you make an adjustment, you are manipulating the "sensitivity" of your clutch. That is, where during the depression of the clutch pedal, the clutch engages or disengages. So for example, if you now press the clutch near the floor before it disengages; you can adjust it so that it would disengage during the first 1-2 inches of travel. It can save effort and time when shifting. If your cable becomes stretched over time, you then can readjust for that extra slack, which is what the stock 2-piece quadrant is designed to do. hope this helps.