The main reason for adult tooth extraction is pain or overcrowding due to wisdom teeth pushing through the jaw.
WHAT TO EXPECT
To get to the wisdom tooth the dentist will need to remove any gum and bone covering the tooth and either pull the entire tooth out or cut it into pieces and remove it piece by piece. S/he will then sew the gum together with a slowly dissolving thread. To offset the pain and allow for unfettered access, the process is usually done under full or partial anaesthetic.
It prevents overcrowding of teeth negatively affecting your smile. If the issue of truculent wisdom teeth is not dealt with sooner it will need to be dealt with later.
Pain and the risks associated with any surgery.