First of all, some conditions that can be discovered through prenatal screening procedures can be treated, and sometimes even in utero! Some people like to have the knowledge that their baby will be born with special needs in advance, to prepare themselves mentally and practically. Some conditions also require special actions during birth, which can be facilitated if prenatal screening revealed the problem in advance. The other reason why many people favor prenatal testing is that they would choose to terminate the pregnancy if prenatal screening revealed, for instance, Down's Syndrome. On the other hand, prenatal testing is not able to discover every medical condition, and some screening tests, like amniocentesis, do carry risks. Did you know that an amniocentesis increases your risks of miscarriage or preterm labor?
In other words, prenatal screening can create complications where there were previously none. False positives are also not uncommon with prenatal blood tests, and thinking that you have a baby who is not healthy is likely to create an immense amount of stress. It is also extremely difficult to start refusing tests after you already jumped on the "prenatal screening bandwagon". If you are willing to accept the baby you are carrying regardless of medical conditions or special needs, prenatal screening is essentially pointless, some argue. Furthermore, the odds of having a healthy baby are extremely high. Prenatal testing is certainly not something to just agree to, without considering the implications. It is an extremely personal decision to make.