For writing a program, the s-expression form might become:

    (+ (* 2 (^ x 3))
       (^ x 2)
       (- (* 5 x)))

Whereas:

    2*x^3 +
    x^2 -
    5*x

Would probably error out in most languages, due to parsing issues and ambiguity. Even worse ambiguity, if you put the signs in front, as then every line could be an expression by itself:

    2*x^3
    + x^2
    - 5*x

Could be 3 expressions or 2 or 1.