It is THE main tool for linear systems analysis (often non-linear systems too). Analog circuit design, filter design, control systems, state space analysis, etc. We do nearly everything in the s domain. Also nearly the only good way to do transient analysis in linear systems. It's all about the poles and zeros in the Laplace transfer function.
In my world the impedance of an inductor isn't L, it's sL. Linear circuit analysis starts and often ends in the s domain, you transform back to time only when you have to.