Here is the thing…
With the Bid in WR, yes, you can still lose both WR AND Ukraine. But with typical dice, if Russia attempts both, they will be thin to the point of transparent on the German front. And then Germany coun counter-attack possibly BOTH WR and Ukraine without significant opposition.
But you don;t WANT to have to re-take territory as Germany on G1. Your AF is needed for other areas of security (the BB off Gibraltar and the DST off Egypt most notably), so you don;t have AF to use for your counters, you have to comit land forces. And if WR is stacked, as it normally is post R1, whatever forces you put in Ukraine are likely to die on R2. And since you AF are tied up, that means German ARM dead in Ukraine in exchange for Russian INF, a BAD trade.
But if you sucker Russia into only attackign West Russia, then you don;t have to re-take Ukraine. That means extra German ARM alive while Germany builds up their INF to start their eastward drive. And of course Germany maintains 6 FIGs, isntead of having only 5… a point that is always worth remembering.