I get what you're saying, but tire technology has improved traction so greatly in the last decade that we can definitely take the slight loss in maximum theoretical traction for the massive benefits in other areas. There is also the question of what "maximum traction" is... what scenario are we talking about? Straight line acceleration from a dig or skidpad turning at a high speed? If we're turning at all then the momentum (which increases w/ mass) of the vehicle is what pulls it off course and causes the tires to break traction.

I also drive a FWD (a quite spicy one) and I break traction all the time, not because of weight, but because of torque. You can modulate torque, not weight. The biggest traction increases that I made on my FWD were when I put on sticky summer tires, the second was subtly changing front control arm geometry and bushings, and the third was adding stiffer engine mounts.

Agreed on getting tossed around in a light car though, not much can be done about that... other than making the roads better and lowering the center of gravity.