Making a Quantum Change
Rashi (11:45) brings a powerful teaching: “The Kodesh Baruch Hu said, ‘If I had brought up Israel from Egypt only for the reason that they do not defile themselves with swarming things, as do the other nations, that would have been enough for them...’”
This is Hashem's own version of “Dayenu.” He is saying that the entire Exodus would have been worthwhile solely to ensure that Jews do not eat bugs!
This raises two obvious questions:
Once we left Egypt, our physical and spiritual needs shifted. Bugs became harmful to a Jew on every level. Hashem forbade them to help us maintain the higher level we had reached.
However, the drive to behave despicably still exists via the Yetzer Hara. Because we once ate these things, we might think, "It’s not so bad; it wasn't repulsive then, and most of the world still does it today" (a practice known as entomophagy). To counter this drive to slip back into a subhuman state, Hashem gave us the commandment of Bal Tshaktzu—to teach us that what was once "permitted" is now, for us, a disgusting act.
As a person grows in spirituality, they become more sensitive to their surroundings. People often mistake this sensitivity for weakness, but it is actually a sign of spiritual awareness.
Take modesty as an example: as a person incorporates more tzniut into their life, it naturally becomes uncomfortable to be around immodest speech or behavior. This isn't out of a fear of "relapsing," but because their spiritual needs have changed. That which didn't bother them in the past becomes repulsive in the present because they are now closer to the Source.