A. Convenience - Easy to make/eat
B. High protein content with little fats/carbs
C. Faster for your body to absorb
What it boils down to is do you like the way protein shakes taste? If you buy economically priced protein powders, generally you'll get more bang for your buck in terms of protein content then you do for most meats (say for bulk chicken/eggs), and be able to take your protein in something which alludes to a milkshake. Do you need to take it, absolutely not, will you see better results with it- probably not significantly better unless you're using it to increase your overall protein intake to a more ideal level. Personally I buy cheap ass chicken and eggs and use protein powder sparingly, typically to sweeten my oatmeal (eggs in oatmeal get boring real fast), but whether it's worth it is a matter of personal taste.