Perhaps this is the thinking of FP -- they said that we would go into the wasteland for valuable resources and the only one that we have so far is the radiated mushroom. Perhaps they could make an expendable? Such as a mini nuke bomb mine? Or they could be used for a laster pistol, which would require steel, mushrooms, scope lenses, and something else. The charge for the pistol would also require the radiated mushrooms. It would have a high dps but low dmg and would fire like the laser in 1993's Syndicate (or Syndicate 2?) -- blaarp and then charge gone. So e.g. 5 dmg x 20 hits per second. Armor stops lasers.
In any case, new weapons would then enable tougher yellow and blue zombies.
In any case, new weapons would then enable tougher yellow and blue zombies.