Memory of Goldfish

If somebody has a good memory, we said about him that he has an elephant's memory. But if somebody has a gold fish's memory, that we can said about somebody with bad memory. Why are all logical games based on principe "puff, remember this and now mark that, what you've seen", has so stupid and simple progress? One blue fish. Blue fish and yellow fish. Blue, yellow fish and ray. Blue, yellow fish, ray and... well, pity.