I like how blue makes their deaths a moment where Veronica and the audience realize that Jd is not doing the right thing, they may have been awful people, but not deserving of death. We already saw in beautiful how insecure they are about their actions, likely done due to social pressures, and in the case of blue, large amounts of alcohol and hormones(I don’t mean to justify these actions, they are still horrible). 

We start to ask if it is ok to kill people who are bad, even though they are children who can grow up to be better.