First: you are obviously a very wise person because you are a Phillies fan and a very loyal person because you advertise that when we are at a time when the Phillies are so bad!
In regards to your question… There are many reasons: from the sanity of life, etc.
For me, one of the reasons redemptive suffering. While it’s hard to see the good in a suffering baby, suffering children can be an inspiration to the world.
For example: look at Alex’s Lemonade Stands. That child bravely faced cancer and tried to use the disease for good. Alex was a true inspiration and a courageous child.
When we see people suffer bravely with dignity or a baby live with suffering, it touches us. We want to do something about it and help. It calls us to help.
When we are formed within Christian morality, it calls us to moral actions. But when we are formed with or influenced by secular or pagan ideas, it can cause us to suggest immoral responses to that call.
The idea that abortion is merciful is based on our ‘call to action’ when we see suffering. However, the lack of proper formation and a warped sense of mercy and morality is what causes people to think abortion is a valid response to the suffering.
For example: if it’s OK to abort a baby who is ill, then why isn’t it ok to kill an old person who is ill (which is exactly where we are now). Then, if it is OK to kill a sick old person, then how about a sick teenager or sick 30 year old (happened on the west coast). If it’s ok to kill physically sick people, why not kill mentally sick people or people who are depressed? If mentally sick people can be killed, then why not kill all criminals? If you can kill all criminals, why not kill all poor people? If it’s ok to kill all of these people why not kill people who the government determines are jerks or lowlifes? If it’s OK to kill government labeled jerks & lowlifes, then why allow me to kill everything I think is a jerk or lowlife?
I know my example goes far down the rabbit hole, but that is what it was like in a pagan world.
Abortion is a throwback from a pagan world and allowing abortion for any reason is validating the pagan practices of pagan society.