While I don't agree with killing off April, or her unborn child, I can see why the producers took the route they did with her. For one thing, she hasn't been seen since the episode in which we got to see what happened the day before the bombs went off. That was certainly one clue that something nasty was coming to that particular character.
Secondly, some woman actually do have complications during a pregnancy. Even in today's world with all of our medical advances -especially in prenatal care, some woman still die of pregnancy complications and/or devliery issues. April had pregnancy complications. And with the lack of the proper medications on hand, the proper equipment, and trained docters that specialize in high risk pregnancies, death was bound to happen to at least the baby, if not both mother and child. Again, I don't agree with killing off April or the baby, as there were still some great storylines that could have been played out. But now that they have killed off April and the baby, other possibilities can happen -like Eric actually being forced to actually deal with the choices he made (in reguards to cheating on April, and then actually leaving April for Mary).
And while he could have dealt with those issues while April was alive, there's also a deeper sense of ... dealing with them, Eric no longer has the option of going back to April, to talk to her, to seek her forgiveness, etc, if and when he'd actually chosen those options.
I wouldn't wish the death of a child, unborn or even as an adult, on anyone. But with Eric losing the baby & April, Eric will do some major soul searching, and hopefully come away from this experience a better man for it.
I don't think he would have done that soul searching, not this spiritually (if you can call it that) deep, without their deaths...