Most news casters, male or female, tend not to be old and they tend to be more attractive than average and often much more attractive than average. Yes, the problem is more obvious with women but it applies much the same for men. The simple fact is people, male and female, prefer watching attractive people even if they themselves complain about it.
The business decisions that motivate the replacement of older news casters with younger ones is just that, a business decision. The odds are very high that the older news caster that is being replaced had earlier in there career, when they were younger and more attractive, replaced an older news caster. But, perhaps we can conjure up a SJW program to demand an end to people favoring attractive young people -- good luck with that!
Brian