Whats the rationale for using taylor series in economics? I've been reading about the translog production function and know its really just a log-log production function approximated using a first order maclauren series.

Why not just leave the function as is? What economic interpretation or use does taking taylor series do for us?
You will gain in flexibility and generality by adding more terms and avoid to impose restrictions on substitution between inputs and returns to scale, that are usually rejected (when tested).