For the average German it is plain and simple not an advantage. Maybe if the export bonuses keep the company you are working for alive, but that is a unrealistic edge case.
I sell SaaS software on a subscription basis to customers all over the world. They pay for our service in USD, which is then converted to EUR when I get paid from the company.
If the Euro was stronger, which it would be if it were only the currency for Germany, I'd get less Euro when that conversion happened, and I'd have less local currency for things like rent, groceries, etc. The Euro being artificially depressed against USD absolutely benefits anyone who either personally or via their company exports products, including stuff like SaaS. Since exports are the backbone of the German economy, it has a very concrete benefit to most Germans. Greece's economic problems literally mean I get more cash.
But wouldn't you be able to still buy exactly the same stuff with less (but stronger) Euros?
This is true in most places without particularly volatile currencies, though in countries that do have very volatile currencies, things like rent have historically been specified in stable currencies like US Dollars, Deutsche Mark or Euro.
Surely things like rent take longer to reflect an increased demand but they do eventually catch up.