There simply must be an answer to why children getting attached to teddy bears or blanket. Actually, there is not just one reason, but there are many reasons. With each different reason is a different child with their own unique story.
The most common reason for this attachment to stuffed animals is the fear of darkness. Little children tend to be afraid of the dark. Therefore, they seek comfort from they're favorite teddy bear or stuffed bunny. This comfort comes from their sense of friendship the get from this special item. Being young, they may not have that many friends yet. This gives children the chance to imagine that their special item is the best friend ever.
Perhaps the teddy bear that these children hold so dear was given to them by a very special person. For example, a grandmother that has passed away or even just their loving parents going out of their way to make their child happy. That would definitely create some good memories. The certain smell of that item may also bring back some good times. For instance, the stuffed toy that the child is so attached to may smell like that apple pie that Aunt May used to make. This is all described in one word; Memories.
The life of a child can be filled with ambiguity and clinging on tightly to a special toy gives them a great amount of security of having something familiar right beside them along the way. Toys give children the opportunity to express themselves imaginatively through the use of role play. They are uncomplaining friends that will never tell the child that it is "much too rainy to play" or "I do not want to be your friend anymore" and they will be strong against a barrage of conflicting feelings and treatment, so helping your Child build up an emotional awareness of his or her surroundings.
Children have a tendency to outgrow their special toys when they start school. However, for others, even after we have grown to full adulthood, it can still be a comforting thing to take out an old and much loved friend and hold them for a while. There is no harm in a child clinging to a stuffed animal. Just be glad that your child has a sense of security and comfort should they ever feel lonely or scared. That would be a load of your back.