Circuit and system designs start from SPICE simulation. Starting in 1970's, SPICE only had lumped element models. Not until 2000's did HSPICE have frequency-dependent lossy transmission line models. Now in 2010's, engineers need more accurate models (in the form of S parameters) for ALL multi-gigabit designs. S parameters are still a novelty to many designers. Easy-to-use mobile-apps-like SI software comes in handy for EEs to create better designs in shorter time.