Hmm. Why You say so? - it is a sandbox game after all. If one does not like said element he does not have to use it. Even the game manual prompts You to alter the game anyway You want.
And in this situation I just want VARIETY and possibility. The same goes with search cards. I would very much appreciate toxic and berserker walkers in the items pile.
Simply enough fix.
Take a few of the spawn cards for them and draw a little black circle on the face with a marker.
It comes up, you spawn at sewers.