Learn English – History of the phrase “for Mother Russia”

From the comments to the OP:

My understanding of the terms "hardcore" and "softcore" come from baseball and softball, and the term "hardcore" at least is roughly synonymous with "playing hardball" which is definitely baseball-related.

More in-depth: Since the early 1900s at least, baseball has been played with the eponymous cork-cored, twine-wrapped, leather-skinned sphere that has near-universal recognition. The only significant change to the "official" baseball used in the major leagues was during WWII when rubber was substituted as the core material to replace cork (which was needed for the war effort). Cork baseballs are small, dense, and not very forgiving; in fact, players have died from head trauma after being "beaned" and been forced to retire after making barehanded catches that shattered every bone in their hand. Such a ball is a "hardball", and playing with it is "hardcore baseball".

The game of softball is not that much newer (1887 vs 1845 for baseball), but it evolved from the game we have come to know as baseball to create a more "casual" game. The name "softball" came from the original construction of softballs; primarily similar to baseballs, but much larger (up to 16" in circumference) and more loosely wound. As the early balls broke in, they really did become soft, and the game was actually originally intended to be played barehanded (thus requiring virtually no individual equipment; just one bat, one ball, and some base markers). Modern softballs are not very soft, and so the modern game is played with gloves (and "fast-pitch" leagues for women use practically all the same gear as men's baseball leagues with the primary exception of "pelvic protectors" replacing athletic cups), but the balls still "give" more than cork baseballs, and more often incorporate softer core materials such as rubber.

The two games have both been around long enough in recognizable forms, along with the eponymous balls used to play them, to be the origins of the terms. My thoughts are that "hardcore" came first, and then "softcore" followed as a complementary antonym. Unfortunately the sexual connotation the terms have gained makes it difficult to do real research into the terms themselves from a work computer. I know the term "hardcore" has been commonly used figuratively since at least the Vietnam War.

According to Google's Books Ngram Viewer, the phrase was coined some time around 1800 and peaked around 1930:

The oldest reference I could find for "olden days" is the 1805 Tobias: a poem : in three parts by Rev. Luke Booker:

And the oldest I found for "olden times" is Poems on Affairs of State from 1620 to this Present Year 1707, in a poem called "GIGANTOMAXIA, or a full and true Relation of the Great and Bloody Fight between three Pagan Knights and a Christian Giant" by an unknown author and originally published in 1682:

I suspect these stem from the Romantic era:

Romanticism is a style of art, literature and music in the late 18th and early 19th century in Europe. This movement said that feelings, imagination, nature, and old folk traditions such as legends and fairy tales were important. In part, it was a reaction to the aristocratic social and political ideas of the Age of Enlightenment and the Industrial Revolution. It was also a reaction against turning nature into a mere science. It showed itself most strongly in arts like music, and literature.

Take for example this 1868 poem called The Olden Days.