First off, the damage to third parties might be extremely severe, especially in a targeted attack. Think of long-lasting power outages due to damaged equipment. Or think of environmental damage (e.g., suppose you got a nuclear power plant to vent radioactive gases, or worse, to have a meltdown).

Second, the damage to the owners of the industrial facility might be severe even if not to third parties. Here the attacker might benefit if, e.g., they are a competitor or have shorted the victim's stock.

The first case is of extreme interest to the public, don't you think?

Let's not dismiss concerns about industrial security.

For your first case, you failed to provide a possible. motivation. I will assume "terrorism" as that seems to be brought up as a motivation for most everything these days. There is more than one problem with this.

First, it is pretty much impossible to prove that an attack over the internet was actually carried out by any particular entity or even any entity at all. Things fail on their own. Second, it is usually easy to entirely prevent another attack. So no ongoing sense of vulnerability.

For your second example, it has always been fairly easy to damage industrial infrastructure but there have been almost no attacks of this kind. Stock market movements are not that severe in the case of even serious catastrophe much less the sort of trivial problems you could cause by attacking industrial controllers on the net.