Not to turn this post into a big "social statement" thing, but it isn't even just the "beauty/brains thing". It's all kinds of things for women. Women have to often be "just the right level of professional looking", which often means not having a "softer" face, not having a girlish look, not having a "softer" hair-do, not looking "too casual", not looking "too old", not looking "too heavy" or "too delicate and fragile", and generally (often) not looking "too-any-number-of-things" for one reason or another. Some women who have "just the right level of professional looking", or at least a look that doesn't mean they aren't taken seriously, may not know how bad it can be. There are so many stereotypes, and there's so much tendency for people to expect women to fit stereotypical images; an awful lot of women can struggle with being taken seriously. On top of that, who any one individual takes more seriously can be different, and there's no way for one woman to fit all the stereotypes in order to be taken seriously by, at least, most people. (Which is why is I see my Earth picture as a good idea. )
Whether someone looks like, say, Betty White, Sally Field, Doris Roberts, Audrey Hepburn, Valerie Bertinelli, or Jessica Simpson - there's a really good chance they'll be people who won't take them seriously.