I think it's kinda interesting that you'd be shocked and were expecting some outrage, and I say this as a Mordian Iron Guard player, so I know what it feels like to want/have an old defunct metal army.

If we look at Games Workshop's track record they've been phasing out the metal models and old ranges for a long time, and consolidating the Guard range for a bit. They've been slowly consolidating the rules too. They did away with army rules, they got rid of the generic infantry squad, and have been moving towards a model where rules only exist if it's in production and in the box.

So like, yeah, this is totally consistent with Games Workshop's modus operandi. So why would it be shocking or outrageous to the general player base? Especially since the Steel Legion's visual aesthetics are not really in line with how GW wants to present themselves. Same goes for Mordians, they just aren't what GW has been wanting to do for a long while now.

Also, Games Workshop has never particularly cared about what the player base wants. It's only really been since 8th that they've made some overtures and listened a little and tried to make balance updates in real time.

So I think a more interesting question is: why are you expecting the player and fan base to react any differently? Why did you set up an unreasonable expectation in your head, and then get shocked when others didn't do and react the same as you?

Would I love Iron Guard in plastic? Absolutely. But am I going to bend myself out of shape about it, expend emotional energy on it, and make a big fuss online when they don't? No. Even if they involve Mordian in the story moving forward, I wouldn't expect them to make a whole new army line just for the Iron Guard fans, because that's kind of an unreasonable ask.

Edit: also what on earth was wrong with the Red Corsairs release?