When Wirth talks about modules and abstraction I believe he was talking about what was known as the software crisis. In particular the observation that as programs size increases the number of possible interactions of program components grows quadratically.

Modules in particular and good abstractions in general make the number of interactions between components tractible.

The N^2 component interaction problem is real and it continues to cause problems.

Even with our best solutions there is room for improvement.

Last I paid attention there was a culture that had developed around the administration of CISCO routers because things that should be unrelated affecting each other is a real world problem for the administrators of those routers.

Any time something changes in siftware and something unrelated is affected this general problem is making it's appearance.

There is also a long term tension between abstractions and entire system simplicity. The wrong abstract or an abstraction poorly implemented can make things worse.