Well, it matters quite a bit ethically. If AI were conscious (I don't believe it is) then we'd have a major responsibility to like, not make them suffer, and not kill them.

Lots of people do though. Daniel Dennett (probably the most influential philosopher of mind in the late 20th century) for example had an evolutionary view of consciousness arguing it was favored by natural selection. And (if I remember correctly) Steven Pinker argued that consciousness was an epiphenomenon.

However there were pretty strong arguments against this idea as early as the 1990s, by Stephen Jay Gould and Richard Lewontin. Gould actually wrote an excellent paper against Dennetts idea[1].

I think Dennetts ideas were extremely popular but have largely fallen out of fashion. Basically what has changed is philosophers no longer take the human mind to be much more special then the minds of other species. What plagued Dennetts ideas the most was this notion of Darwinian fundamentalism sort of the idea that evolution was destined result in high beings like us humans. Modern philosophers (at least the good ones) reject this.

1: http://cogweb.ucla.edu/Debate/Gould-frame.html

I think consciousness could be a side effect of our limitations. The fact that we can pay attention to at most 2% of our visual field and need to move it constantly around to provide more training data and prompts to "smart" path in our brains. And the movement is physical so it takes time. And processing the information through the loops in our brains takes time. And you can't pause it. And we have the same attention motion system virtualized in our dreams to burn in our memories into chemistry. We are biologically single threaded. If we create similarly limited, embodied AIs we would feel they might be conscious at least at the level of animals. Because they would exhibit conscious like behaviors that we didn't program in.

Look at jumping spiders. With a handful of carefully trained neurons and a body to match they exhibit behaviors that make it very hard to think they are not conscious. Just because they have a body, narrow angle good eyesight and need to look around with their eyes and body.

Consciousness is a red herring. Of all possible intelligences conscious ones are the bottom rung of the ladder, easily simulated by anything above. Below there are only automatons.