Everyone had designs on "controlling the thing", and the ability to do it: France had long set the EU agenda, BeNeLux and nordic countries were seen as the "reference implementation" for most processes, Spain was extremely aggressive in occupying key roles (Javier Solana, anyone?), even the UK was quite good (watering down ambitions of full political union, basically)...
The real game-changer was the rushed enlargement. Now Germany can count on a political bloc of countries directly depending on the German economy, and for anyone else it's much more difficult to steer the boat with so many people on board.
The real game changer is that in many areas German policies worked better than others, especially in the current economic climate. Ten years ago this was open. Countries like Ireland were seen as 'Tigers'. The UK was adopting the service-oriented economy with a large banking sector boosted by North Sea oil and gas. Germany was struggling with the reunification.
Now Germany has high debt, but was dealing with this problem years ago to keep in under control. More has to be done, but we are further than we thought.
The industry is more competitive in terms of delivery capability, production technology and products.
The decentral structure of the country enabled competition within the country - between Berlin, Munich, Stuttgart, Köln, Düsseldorf, Leipzig, Dresden, ... there is no such central structure like in France or the UK.
Key was to keep employment high. Youth unemployment is very low. General unemployment is on a 20 year low. This kept people confident. Confident that they have enough to weather this economic crisis. Germans save more, they speculate less and many prefer renting instead of owning (and being in debt).
There were some mistakes made (like some of the German banking system failed), but in general it looks okay.
Yes, but in terms of governance inside EU institutions this doesn't matter as much. If we had a situation were Germany was doing very well, but everyone else wanted to tweak the currency in a different way, it would go in a different way. As it is, thanks to the enlargement, on economic matters Germany can rely on a block of "faithful" countries whose self-interest is perennially aligned.
The real game-changer was the rushed enlargement. Now Germany can count on a political bloc of countries directly depending on the German economy, and for anyone else it's much more difficult to steer the boat with so many people on board.