The truth is that you really do not "need" algebra unless you plan to teach it or use it in a scientific profession. Just like you don't need to lift weights or shoot baskets unless you plan to be a basketball player. But before you put away your algebra books to shoot some hoops, let me give you some good reasons "for" learning algebra.
Algebra is a very unique discipline. It is very abstract. The abstract-ness of algebra causes the brain to think in totally new patterns. That thinking process causes the brain to work, much like a muscle. The more that muscle works out, the better it performs on OTHER tasks.
In simple terms, algebra builds a better brain (as do other disciplines such as learning an instrument, doing puzzles, and, yes, even some video games). When the brain is stimulated to think, the hair-like dendrites of the brain grow more extensive and more complex enabling more connections with other brain cells. We often hear that we use only a small percentage of our brain's capacity. The study of algebra is a way to increase our use of this marvelous muscle. By studying algebra, more "highways" are "built" upon which future "cargo" is transported -- cargo other than algebra.
My favorite analogy is comparing learning algebra to the construction of the railway system in the United States in the 1800's. When railroads were built, surely those men never conceived of the items that would be transported on those rails more than a hundred years later. They could not have imagined home appliances and computer equipment traveling over that railway system. But they knew that building the transportation system was important.
So is it with the study of algebra -- you learn algebra by transporting numbers and variables -- later, those variables will change and you will transport something useful for your purposes.