Why don't Retro racers use true Retro chassis from the '60s and '70s like this?
Well, David, I for one am glad we don't. For any class of racing to succeed you have to have other racers to race against. I was there in the '70s racing in Australia and overseas and I'm glad it's finished. A huge skill set was required to build and race these things. In Australia to succeed you had to be the whole package and build our own chassis, motors, and bodies. To get a following these days to do that is just not going to happen.
Whoever did the Retro rule set has done a pretty good job. It's a good balance of racer and retail. I've just come back from racing Retro at Hornsby and we had about 25 cars. The interesting thing is almost non of the racers have actually built their own. In most cases they buy a ready-built chassis... and simply screw in a motor, get some wheels out of a bottle, mount the body, and you're away. (Non of this burning finger stuff soldering in the motor while trying to get the right mesh.) And best of all the low torque Chinese motor don't want a track bogged down in glue so the track owner is not going to have the Flexi brigade smoking motors after the race.
Be there, done that... I'm not going back.