There is a legitimate debate to be had over whether the diversity lottery is worth keeping. It amounts to roughly 10% of the annual immigrant visas issued (the vast majority go to people with relatives already in the U.S.). The program began in the 1980s in an effort to add more immigrants from Ireland and Italy who faced long delays in obtaining family visas because of national caps and huge backlogs. At the time, both countries faced significant economic problems, but as those economies stabilized, and with the advent of the European Union, there was less demand, and more of the visas began going to people from African and Asian countries.
Source: latimes.com – Los Angeles Times