There is an important reason for the hole at the top a BIC pen lid and it is not about preventing the ink drying on the nib. The pen caps have holes in them to prevent suffocation, in case they were swallowed.
One of the oldest and more popular ballpoints were the Bic Cristal who originally made it part of their design to include a small hole at the end of the cap. Considering that pen caps were one of the common objects swallowed by children causing them to choke and proved fatal. The hole was put in to allow passage of air in case the dreadful event happened; since, we all love putting them in our mouths!