Pacifiers are very useful for babies under a year old and can help prevent SIDS.
But really a child does not need a pacifier after age 1 year old as they can do more harm than good.
The pacifier use past age 1 can lead to crooked teeth and eventually lead to speech problems if the child has the pacifier in his/her mouth constantly.
However if your child will not give up the pacifier until 3 or 4 years old that's okay and it's not really worth fighting about.
Some children will eventually give up the pacifier on their own without any fight but if the child is 4 years old and not giving up the pacifier on their own you really should intervene and take it away.
A child cannot go to kindergarten with a pacifier or they would be teased and tormented by other students in the school which not a good thing.