Originally Posted by Roelof

Lightweight cars is one reason. With Life and LiPo you first gonna put weight where you want it, in the battery tray. In that case why not sticking to heavy batteries? Also LiPo is not the right choice (anymore), people have experienced what extra electronics and in this case switching regulators can do to a reliable working receiver.
And last thing with exploding LiPo batteries. More clubs are making rules that Lithium based batteries must be charged in a LiPo bag and with balancers to prevent the small chance of an exploding battery