Ignoring the cognitive stuff which might never be surpassed or maybe will, humans retain many efficiency and durability advancements to limbs and digits that biological evolution has taken millions of years to achieve, achievements that are competitive with the most expensive kinds of robotics in some niches.

In the hypothetical of an entirely malicious and selfish takeover, they'll still keep some humans around to maintain a breeding population of humans for use as raw materials in making cybernetically augmented technical laborers for various kinds of tasks that are uneconomical to automate in other ways, many of which may involve confined spaces.

And this "Combine" scenario, if you get the reference, is only if they take over. Who knows if they will?