YOU’VE LIKELY heard of 4K, the new super-high-definition television format that has the consumer electronics industry in overdrive. “Buy!” it’s been saying, “BUY!” You may have even seen a 4K television in all its glory at an electronics store, its crazily precise images of flowers so real you could reach through the screen and touch the petals or—why not?—smell them.

“But 4K is expensive,” you discovered. “4K is confusing,” you thought. “Avoid it,” you eventually told yourself. After all, you just bought an HD TV a few...