First point I'd much rather 'nick' a wirecore while being TIT and not have to fall into my second tie in with a running saw. But again I've never tested that out.
To your 2nd point. I climbed and rigged spars for five years with just a steel core flipline and as Wiley P mentioned when bumping limbs it's definetly not false hope compared to a non-wirecore.
To your 3rd point as I and Wiley P have mentioned it's the medium to decent sized conifers that the stiffness of the wirecore gives an advantage on imo. We don't have redwoods up here but I can't imagine to many people are 'rolling' a steel core on the huge suckers.
To your last point, making up your own lanyards is definetly a nice thing to be able to do, but regardless at some point in time you bought the rope/hitch cord that you're using to do so.
I have no problem with people not using a wirecore, what would I really care if they did or didn't? As to RD's original inquiry, he's a young go getter and as DMc has said learning a multitude of techniques with all different types of gear is only going to benefit him and help him build experience to base his own decisions/refinements on.
I have no doubt Tophopper that you're a much more talented climber than me and through your experience you've refined your gear and use what works well for you. I've tried flipping spars with a non-wirecore light line and I found it very ackward. Wirecore works for me so I stick with it.