the article linked above ignores the religious context in which the current controversy over depictions of the Muhammad in cartoons arose.
Yes, it ignores it. That's because it's not about that.
In papers and on websites everywhere right now, debates are being had about the depiction of the supposed "Prophet" Muhammad, and whether or not people should make such depictions and whether or not there are laws, or should be laws, against such depiction
Great! All the more reason to look into where the idea of aniconism comes from.
Into this debate, the Spectator has floated this misleading essay, with a misleading title, saying, in effect, that the whole thing is a misunderstanding, since depictions of the supposed "Prophet" (why is this madman called a prophet? What did he prophesy, apart from the murder of his critics, the capture of slaves, and the rape of captive women? Apparently nothing whatsoever) Muhammad isn't actually banned by the Quran.
I don't know who this Barnaby Rogerson is, or what he's said "in this debate". Maybe you do, and maybe that's the reason why you read this article as saying that the whole thing is a misunderstanding. The article, as I read it, corrects the misunderstanding that aniconism comes from the Koran, and looks at its historical source and interpretation. What he's saying might be wrong or one-sided, but I wouldn't know, I'm no expert on this.
what is banned and not banned (e.g. haram and not) according to Islam, cannot be ascertained by mere reference to the Quran, since Islam is also based on the Hadith, the literature which recounts the sayings and actions of the supposed "Prophet".
That's one of the premises of the article! The whole article from the second paragraph on is based on the idea of aniconism coming from the Hadith.
Since that literature unambiguously shows the supposed "Prophet" ordering the murder of his critics, the net effect of the Spectators article is to deceive the reader as to what Islam actually calls for.
The net effect? There is no 'net effect' of an article examining aniconism and an unmentioned Hadith advocating murder of critics. The article is about aniconism, its sources and interpretation. You're the one talking about murdering critics, which is a different issue altogether.
This article contributes to confusion about it, by focusing on only the Quran, while Islam has another body of literature, unexamined by the piece.
Jeez! What will it take to get you to read the article? The whole article except the first paragraph is about the Hadith and its interpretation.
Islam clearly says that critics of the supposed "Prophet" Muhammad should be killed. That is true and relevant.
According to your quote, the Hadith says that. I have no interest in arguing that it doesn't. To get to what "Islam clearly says", however, one has to take other things into consideration. Although I don't think the article is particularly thorough in its treatment, it does in fact exemplify a way to examine the meaning of a faith by looking at its different traditions. Such a treatment is necessary. Otherwise, you're standing with an ancient quote and nothing else.