It may be revealing to just observe robot evolution in time, both in reality and fiction. In fact, robots in fiction did not evolve much from a functional point of view until Asimov pointed out that they might have a soul. From the very beginning, they were designed as humanoids or, at least, animals, capable of reasoning up to a limit, yet devoid of free will. Indeed, all robots up to the XXth century, from Hephaestus' assistants to the golem were just supposed to serve human kind, but they could reason on their own to do so.

RUR changed this concept, as robots became a metaphor for opressed social layers in the middle of the Marxist Revolution, a trend that Metropolis was happy to follow. Asimov went one step further and, from the 60s on, robots started to have their own personalities. Still, they were mostly humanoids, until real robots started to be constructed and it became obvious that they would not be ironing our clothes anytime soon.

Star Wars changed this view up to a point: aliens were no longer humanoids, so why should robots be? Instead, we could plug and play R2D2 in our X-Wing or ride 4 a legged ATAT to destroy the Alliance, leaving human shape for protocol droids like C3P0. The next 10 years would not change things much, except in terms of AI: machines would get fed up with human supremacy and revolt against their creators, that mostly wished they had never stopped finger-counting.

The next big r-evolutionary step came with BSG, where robots had evolved so much that they became flesh and blood and the frontier between their kin and humans became so thin that noone was really certain about their nature anymore.