Its just we don't call them kitchen computers. We call them smartphones and tablets, and they're even more embedded in our lives than many of these 1970s futurists could even imagine.
And yet at the same time we're still nearly as far off from truly completely automating the kitchen. I still don't have a machine that I walk up to and it can make me a wide variety of meals with little to no interaction on my part.
Probably like a billion dollars to develop the first prototype, and each copy would be in the hundreds of thousands of dollars range, maybe eeking down into the tens of thousands of dollars range if they work really well and become inexplicably popular. Even then it would be up to the customer to keep it stocked with ingredients in a specially designed containers in the included pantry and refrigerator.
It's really the same reason McDonalds never really went through with that fully automated restaurant threat. A person can do the same job for minimum wage, so the robot will never be cost efficient unless someone else does all of the R&D for you, and even then it's highly dependent on being low maintenance.