We have history classes for that.
Those cities were laid out as a giant prayer to power. Germany is in no position to preserve their past.
Read a History book dude, Leipzig, was not built to a "master plan" or laid out as some sort of symbol of German power. For hundreds of years, Leipzig has been a commercial center and was, and for that matter, still is the site of a famous Trade Fair which dates back to the middle ages. Besides, as an American, YOU lack the moral authority to pass any sort of moral judgement on Germany or its people!
Leipzig's name is derived from the Slavic word Lipsk, which means "settlement where the linden trees (US; lime trees in UK) stand".
First documented in 1015 and endowed with city and market privileges in 1165, Leipzig has fundamentally shaped the history of Saxony and of Germany. Leipzig has always been known as a place of commerce. The Leipzig Trade Fair, which began in the Middle Ages, is the oldest remaining trade fair in the world. It became an event of international importance.
The foundation of the University of Leipzig in 1409 initiated the city's development into a centre of German law and the publishing industry, and towards being a location of the Reichsgericht (High Court), and the German National Library (founded in 1912). The philosopher and mathematician Gottfried Wilhelm Leibniz was born in Leipzig in 1646, and attended the University of Leipzig from 1661–1666.
The importance of the Trade Fair and the University in the creation of a vibrant urban life and city politics from the Reformation through the 19th century cannot be overestimated.