There is nothing wrong with using a blender. But access to a blender isn't always possibal, or desired. You might be at work, or in the car on a road trip, etc. Some people bring their shaker to the gym with the powder in it so when they are done working out they can add water at the fountain and get there protein asap. And cleaning out the blender at home isn't always something to look forward to.
I like to use a fork more than using a spoon, but even that can be ruff. Just use a shaker and shake it like your life depends on it for 10 - 20 seconds. If its lumpy, add more liquid.
