Computers on the other hand can already be argued to be smarter than a human - if you consider the entire internet as a single computer.
The difference between a robot and a computer is that the computer is self-mobile at the very minimum. If it can't get up and move away, (no matter how awkwardly), it's not a robot.
Mobility is hard, not easy. Worse, the larger a computer is, the harder mobility becomes.
There are lots of reasons to build a computer smarter than a human being, but practically none to add in the huge expense to take that human level intelligence and make it mobile. We already have real humans for those jobs that require mobile intelligence and they cheaper and easier to care for.
More importantly, there is little to no reason for us to build a computer that, being as smart as us, would want to be us. Star Trek's Data is poor planning. Why make it want to be something it isn't? Don't we have enough body issues of our own without giving them tour computers?