People do want to adopt babies. 
Just because they want to adopt, doesn't make them suitable for the task at hand.
Do you think being adopted really worse than never being alive at all
This is a bit of an abstract question, but I'll try to answer it.
Imagine you are a 20 year old woman. You were put up for adoption because your mother gave birth to you when she was in prison. Your first 60-90 days on this Earth are spent in severe pain as you are detoxed from the substances your mother was addicted to. No one wanted to adopt you because you have FAS, so you grew up being passed around foster carers. When you got older you were put in a care home.
When you were 12 years old you met a "nice man". Nice man said he was in love with you, then proceeded to sexually abuse you, drug you, and pimp you. He was violent to you and raped you on a regular basis.
When you reached 16 years old, you were turfed out of the care home and put in a hostel with more drug addicts. You became addicted to heroin. At 17 years old your first baby was removed and put up for adoption - you don't know who the father was, he was probably a punter. Every 9-12 months you continue to have babies that are put up for adoption. You are too addicted to drugs to get contraception sorted out.
Eventually your life style catches up with you and you end up in prison, 7 months pregnant with your 4th child at 20 years old. You didn't realise you were pregnant until you arrived, because you are so addicted to drugs you didn't notice. You have been sentenced to 24 months in prison for drug dealing so your baby will be removed at birth again. You have venous leg ulcers and a PE. You cannot be detoxed from methadone as you are pregnant, meaning your baby will be addicted to opiates when it is born.
Why is allowing this cycle to continue "because we can't abort babies" a good thing if a woman feels the need to have a termination at this point?