Why were the years 1870 to 1914 disgraceful as a period of imperialism in Europe?

Between 1870 and 1900 different European Powers extended their control over vast areas of the world.

Any territory overseas, whether desert or swamp, was considered to be conquerable Germany, Britain, Russia and other European Powers gained considerable territory in Asia and Africa.

There was imperialist expansionism even before 1870. But in the post-1870 period economic gains was the sole motive of the European Powers behind their imperialist expansion.

It was because of this that the imperialism of the period between 1870 and 1900 is considered disgraceful.