R4 is (or meant to be) for those who couldn't afford R5, so there is ERC2, ERT2 and other lower tier championships/classes to fight for class win, or national championships fight for overall. no way that someone will use it in WRC for full program, only for selected events maybe. It is not for making wins in RC2 cheaper it is for making gap between R2/R3 and R5 smaller.