One should note there are... some cards from years of old, with no cost and a reference to Japanese culture. Samurai, Shogun, Samurai Princess, to a lesser extent, Ninja -
they are each great cards, with powerful effects in their respective decks.
Why are they free? In an argument made from value, Samurai will discard uncommon to rare cards against more than half of every deck, Shogun will have absurd effects in any deck you'd place him in(which by virtue of limitation reduces the cost, as with Dwarven wall, but, to nothing?), Samurai Princess...well, would be a hyperbole to say she wins you the next few rounds outright, but she gives a massive advantage, in comparison to other free rares as well as in general, and no recompense to the opponent.
And, from a stand of realism, which is not always followed in a card game, of course... Do none of them need to eat, train, repair their equipment, a place to live or anything of the sort you'd need to pay for? I imagine Halfling rogue is a friend of yours who does dirty work for you off the clock when he has the time, but, I would expect a Samurai Princess to have a full entourage of bodyguards when she isn't on a mission no matter how good your rapport is. Is the Samurai a rice farmer otherwise who picks up his sword for you out of the goodness of his heart for no recompense? Is he in the combat for the challenge alone? A, little romanticized, when the Duelist costs 10 Recruits with the same concept.
Ninja is a good card as far as his value goes, and he isn't free by any measure, but how he sets the cost of his services in accordance to your regular income irks me. And the Shogun just doesn't make any sense.
And I.. can't see any more cards for whom the same complaint would be justified. Only the ones with eastern names. I feel the fact is just a coincidence rather than bias of some form, but, what's the explanation? They aren't outrageous, but I could not, with my personal abilities, justify them to be zero-cost. I would say a little increase in cost would be justified.