Sorry for being unclear.
What’s the greatness of the Jews’ demonstrating their desire to separate from Mitzriyim at the time of Mitzriyim’s punishment?
Their desire to remain separate was shown before makos, so what is the significance of these acts during the last maka?
Also, unlike Jews in Mitzrayim, Lot’s wife wasn’t persecuted in Sdom; her memories of Sdom were more pleasant than Jews’ memories of Mitzrayim.