The current hybrid 4WD are just a mockup of real 4WD. It's marketing stunt which obviously work as You believe in it...
Those cars You speak about are simple 2WD with a part-time availability of pseudo-4WD. The problem is that front and rear wheel drive are not connected and the electric engine for the helping function is just too weak. If You for example stand in a hill and the front (combustion engine powered) axle looses all traction You have only the electric engine in the rear to move all the car which in some cases is not enough to move the car at all (in steep uphill for example)! It also has not enough battery capacity to use the electric rear axle for reasonable time (don't know if cooling allows that anyway). It's just helping system for occasional troubles of common users, nothing more.
None of those cars is electric powered full 4WD car with combustion engine working only as generator which is the only way how this could work for permanent use (basically like in a diesel-electric railroad engine). For WRC use there is also big question of reliability and safety of the electric systems in WRC conditions. It's not F1 or Le Mans but there are water splashes, mud, sand etc. everywhere.
I heard next year Tom Coronel will try to finish Dakar in full-electric variant of McRae buggy. Than we'll see if the electric systems can survive use in real tough conditions (not speaking about the need to change batteries in stages).
If You believe that design of WRC-suitable hybrid or electric system is cheaper than the S2000 You are very very naive. Absolutely no way. Plus with full electric cars You would have to change the format of rallies completely to allow them changing batteries between stages (likely to forbid very long stages at all).