How do you know its not based on merit? I don't know what you mean by "higher tiers" of reporting. Erin Andrews on CNN is gorgeous and even Rachel Maddow would be attractive if she gussied up a bit and lost the attitude. All the past female high powered news people were attractive and they wouldn't have gotten where they were without being at the top of their game. Its not mutually exclusive.
The underlying assumption with all this is that these ladies - who, as has been discussed are mostly sharp if not uber smart - are victims of exploitation and objectification. They're being objectified all the way to the bank, yo. Ultimately it comes down to ratings. Beautiful women get higher ratings. Fox or any other news outlet has no obligation to be "fair" to unattractive women.
Plus, everyone is forgetting Greta Van Susteren who occupies a spot on prime-time. She recently pushed Sean Hannity out of that spot. And it gain because of her looks.
In local news media, you are likely to see doll-like people of both sexes. Local media usually relies on the anchors to do the actual reporting much less, so merit isn't quite as important.
See, this is just what I mean. Rachel Maddow "would be" attractive, if only she conformed to your standard of beauty.
Most people will find younger people in general to have some degree of attractiveness, and Maddow is a bit younger than most of her rank. But she is not conventionally attractive; she is reasonably fit, and seems to have good skin.
But that's not enough to you, because she doesn't fit your concept of "pretty," which presumably involves long bleached hair, short skirts, and more obviously colorful make-up (although Maddow, like all TV people of either sex, does wear a lot of make-up on set).
The fact is that Maddow never would have gotten a job at Fox, because Fox cares more about the sex appeal of their female anchors than they do the substance.
While MSNBC is, in my opinion, not any more watchable than Fox on the whole, this does display an obvious difference between the conservative concept of women and the liberal one. There's room for women with all kinds of looks in both mainstream and liberal media, but not in conservative media.
And no, not all networks put looks first, and MSNBC isn't alone. You think Fox would have hired Becky Anderson of CNN? How about Moira Stuart of the BBC? Absolutely not. Hell, I doubt they even would have hired Tamron Hall, despite the fact that she is very attractive. No matter how qualified they were, Fox would have thrown their resumes in the trash, because they're not blonde and scantily clad.
Oh, and that's another thing. Yes, the pretty female anchor is still common everywhere, but they get to wear normal clothes on other networks. Not on Fox. Anyway...
Fox requires sex appeal first, and merit second (granted, some of their anchors are very meritorious). Everyone else is slowly letting go of the idea that how women look is what defines them as a human being.
I don't claim to speak for how the women of Fox feel about the whole thing, and whether they feel objectified by it is ultimately all that matters on that particular front -- and as of yet, they are quite silent.
But the larger problem here is that Fox is staying in the stone age of viewing women as decoration and sex objects, while the rest of news media is slowly moving away from it at varying speeds.