Thinking of it theoretically, you can't win wars without support type fighters, ie. combat medics, archers/ranged shooters, etc. Yes, in the broader perspective it is misogynistic to make the new female-restricted class a support class when the male class was a frontline unit, but there isn't anything wrong with having a support class.
I'm pretty sure most people can't beat an FE game without using a healer (possible on easier modes, but it's not going to happen in harder modes face it). We don't even know yet if this is a solely support class anyways, it might still come with swords or lances.
Just don't forget the Eirika's class isn't just restricted to healing, regardless if she gets a third weapon, she DOES have bows which makes her a physical unit, impractical dress and all. And you can't say her having bows is just shoving her into a strictly female role, this game has Viole after all.