1. More print area – Especially useful for small size tablets which require a lot of text to be printed on it.
2. Packaging standardization – Every strip(s) of medicine are packaged into small cardbox box and then packed into bigger boxes and then distributed.
By providing extra space / material, a company can standardize a box size and still keep same qty of tablets in the box. It helps them save a lot of costs as they need to buy the same basic size box, only different print on it. Also, the pattern makes for efficient packaging as shown below:
A single strip may look like this
And packed together may look like this
3) Many a time, the retailers give only a fraction of strip to their customers. This can often leads to situation where the details of tablets like name, chemical composition and expiry dates are cut-off / separated. For some tablets, whose unintentional dosages / use has really bad effect, it is an effective way to ensure that all printed content stay with the tablet even if it is sold 1 tablet at a time.
4) Psychological effect – This was mentioned in one of the answers below. Fits in with the “Bigger size, better product, higher quality, high price, blah..blah..blah” kind of funda.