Statistical Confusion

Over at Marginal Revolution, Tyler Cowen links to an article discussing "the winners" of the Euro's devaluation. It defines winners as the countries with the largest percentage of exports since a weakened euro allows foreigners to by more exports. Here's the article's conclusion

The Eurozone nations are impacted quite differently by the fluctuations in the euro. Ireland benefits the most from the weaker euro - far more than Germany as a percentage of its GDP. Because of euro's weakness it was the only Eurozone nation that saw its manufacturing markedly improve recently. But this also makes Ireland vulnerable to EUR appreciation, particularly against GBP.

I do not have any issue with the data used. My concern is over the conclusion. Why does a country benefit from exporting goods, especially from a weaker currency? This is a point I've never understood about common economic thinking. Why is sending more goods abroad seen as a net benefit? Don't people want to receive goods instead? No one would draw the conclusion that McDonald's is doing better since it is selling more hamburgers at half price. We need more information about costs.

I might be missing something in the logic, so can someone please clarify it for me?