Longer answer:
The fact that anyone felt the need to ask this question says to me that we're doing education wrong in the USA. Very wrong. Fundamentally wrong. Yes, algebra is necessary, possibly more necessary than any other branch of math, because there are so many other fundamentally useful concepts wrapped up in it -- formal logic, proof, and a whole bunch of other basic building blocks of epistemology, not just mathematics -- that IMHO it's crucial to teaching students to think and reason answers and not just churn them out by rote memorization the way they do with arithmetic .. the way we're currently teaching it.
But why are we approaching the subject as though it's something "hard" that we have to "work" to learn and then question whether the effort is necessary? The only reason we have that view of it is that by the time our kids hit algebra, they've had all the curiosity and fascination for new knowledge hammered out of them, by normalizing their curriculum to death assembly-line style. Arithmetic by addition and multiplication tables and memorization is boring, mind-numbingly so, and any kid who gets through that gauntlet and is still interested in algebra didn't learn his/her math in the classroom, they learned it by exploring and playing around with it and getting a feel for number theory and how arithmetic operators work .. you know, real math, the kind that gets the imagination flowing.
And if you haven't had curiosity crushed out of you by memorization drills, algebra is fascinating. If you're teaching it right and letting the math itself do the teaching, you'd be hard pressed to stop kids from learning it. Case in point: In my 6th grade math class, a "substitute" (who I'm fairly sure was actually an education researcher experimenting with math teaching methods, but "substitute" was what they called him) came into the class, which was starting on basic algebra, and taught us what turned out to be differentiation by the power rule. I ended up using that one method in every math class I had from then on -- much to the consternation of my teachers who weren't quite sure how to deal with me doing differential calculus on high school algebra tests -- but I also ended up exploring how polynomials went through simpler and simpler derivatives until they ended up as a constant, and then zero, and gained a whole new appreciation for how they worked, and later on, integration and the fundamental theorem of calculus just sort of fell into place. The power rule is still one of my old friends when it comes to math. But I have that "substitute" to thank for most of the algebra I learned on my own because I couldn't get enough of it -- that one little seed sparked a whole adventure that continued to teach me mathematics for decades afterward.
Granted, I'm a hardcore nerd in a lot of ways, but I'm not entirely sure that's an aspect of who I am and not just an artifact of a society raised on the "math is hard" meme. It's hard, yes, but it's irresistible to a curious mind, and we're all born curious .. it's how we bootstrap every bit of knowledge we gain firsthand about the world. If we stop killing it in the schools, give it a few generations and our PolySci professors wouldn't even think to ask this question..