I drive mine, modified with turn indicators and LED tail and head lights regularly.
However, "modern traffic" for me is quite different than modern traffic for other people. My "around the block" loop is five miles of two-lane country roads, going through about a 50/50 mix of fields and houses on 3+ acre parcels. Generally, cars can be seen from some distance away, so being a defensive driver is relatively easy.
I can drive down to the beach (about 50 miles) on similar roads, with short ventures onto four-lane highways (not interstates). I can maintain an easy 55 mph in my cars, and when the speed limit goes above that, I maintain the same speed and let people around me.
Would I take my car into a large city and drive around? Probably not. But for a more rural area, it's okay and I don't feel any more unsafe than I do in any of my modern cars.