How come toy hippos are always blue, or purple, when real hippos are brown?  

Because brown it´s to dark to get a child attentions :)

wel it will look ugly

well they will look ugly

It's marketing stragedy. A child will get attracted to a toy in a bright color, than a dull brown.

to attract children.

well in brown toy they will look ugly so they are made more colourful so that children can play with them