Some people think that issuing bonus shares can be beneficial for share prices. The logic behind this is that the increased marketability of the shares leads to increased demand. This, in turn, pushes the share price up.
The other side of this it is while bonus may seem good, they actually give investors nothing they didn't already have. In substance, it's just a way of breaking up the same company into a higher number of shares and distributing these additional shares pro-rata to shareholders.