It has occurred to me over the course of my first year here at UCLA that mathematicians used to be very good at Euclidean geometry (take the Principia as a prime example, or the early solutions to the Brachistochrone problem)...and over time that has faded. I personally have never taken a course in the subject, and beyond simple facts, I rarely have ever needed it. Though I can see its used in modeling/solving some problems; for example, it was useful in geometric optics/physics problems (but these are mostly lower division/basic problems not requiring a lock of postulates/theorems/etc.).

Yet in looking through some of these forums I've noticed that a good number of people here are actually pretty good at it, and there are many questions pertaining to the subject. So I guess this is now a two-part discussion. Is it worthwhile to become more skilled in Euclidean geometry (i.e. take a rigorous course in foundations of geometry)? And why do you suppose hardly anyone knows the subject anymore?