2.4 million killed according to Rashi in B'shalach. Why does no one talk about it?

Question

In the begining of Parshat B'shalach, Rashi says that one p'shat for "Vachamushim" means one fifth, because during Makas Choshech, 4 out of 5 were killed out, and it happened during the time it was dark so that the Egyptians shouldn't see (although, I'm sure once that darkness went away,they would have noticed a HUGE difference in the Jewish population). If you do the math, 600,000 went out of Mitzrayim, which means that four fifths = 2,400,000. My question basically is, why is there no mention of this anywhere? Why were these people killed out? Why are we celebrating the g'ulah of 600,000 while 2.4 million were killed out? This has always bothered me.....

Answer 1

The Jews that died, did not want to leave Mitzrayim.

Because of these problems Rav Shwab says that the Medrash should not be understood literally - rather only a relatively small number died, but had they lived they would have given birth to millions of people over several generations. The three opinions are arguing about how many descendants would have come from those that died. He suggests that perhaps all they disagree about is how to make an accounting of the survivors - one holds that we measure up to a certain point in time such as the building of the Beis HaMikdash, and another measures to a later point and consequently there are more descendants over that longer period.

http://rabbiygefen.blogspot.com/2011/01/long-term-consequences-bo.html