Just some thought!!
Hashem has created us [Yidden] to fulfill his Rotzon/will and bring him a Nachas Ruach, he has not created the man and his desires so that we should enjoy the Olam Hazeh and all its perks, but rather for the sake of coming closer to him and fulfilling his will, so all the distractions from Hashem (like lust and other bad traits) were also created for that one purpose that the human should rise through working on those desires.
What R' Tzodok means is, that ones Zerah was put in place for the sole purpose of the reproduction of the human [and fulfilling the Mitzveh of Onah pleasuring your wife] other than that it would be like throwing fresh food in the trash bin and even more [wasting of children, and producing demons]so the Derech Eretz would demand to withdraw of this behavior.
again just a thought!