According to The New Yorker's new profile of Danes, Silverstone was as good as locked in, when one of the producers raised a small concern: Since Angela Chase had to deal with all sorts of real-life dramas (drug addiction, binge drinking, and promiscuity, to name a few), there was worry that Silverstone was too traditionally pretty to handle it all. As producer Marshall Herskovitz told the mag, "Alicia is so beautiful that that would have affected her experience of the world...You can’t put that face in what’s been written for this girl."
While we'd argue that Claire Danes is just as gorgeous, we have to admit that we're thrilled the show turned to Danes instead (no offense to Silverstone, of course). And, we don't even want to think about what our childhood would have been like if the actress had been to busy with My So-Called Life to do Clueless. (The New Yorker)