none of the 20 countries that are in the Eurozone have complained
"Countries" might not have complained - politicians are after all mostly venal wh0res. However, people in many countries definitely have complained (e.g. in Slovakia and Croatia). As for older Eurozone members...
... you can see who benefits. Politicians won't complain (their salaries are good :)) but ordinary people in most eurozone countries would be better off with their own currencies.
Even the Czech Republic is thinking about it.
Oh, yes - Czech polticians are also open to be bought, I'm sure. It is ordinary Czechs that I worry about.