On the other hand, being aware of the wider context may improve quality of the result.

Isn't "improving quality" a value for a good computer professional?

It is rarely important from the moral standpoint, since most things that programmers write (or things that most programmers write) don't have knowable moral impact.

I disagree, but I don't have data on the sorts of things most programmers write. In my experience, computer programs impact the lives of people (or why would you write them?) and therefore almost universally should be considered from the moral standpoint.

I do associate primarily with programmers in the 'hot topic' fields for computer ethics - web surveys, data mining, military applications - so that may skew my perceptions. It's significantly easier to see the connection between ethics and one's work when one is working on the system a robotic soldier uses to determine how much damage it's allowed to cause to a nearby hospital.

But I would argue that this blog is either in that category or not performing its function. Eliezer argued that it was worth his time to work on this place because it contributed to his (and the SIAI's) mission that will change the shape of the future of humanity. If that's true, even minor changes here can be expected to have more of a 'moral impact' than most things, military robots included.