I know this is in some way a different version of the prior question In i.e. a TO-220 package, why is mounting the (pin connected) tab to case safe?
But I am not looking for ideas what to do to mount a TO-220 (in my case an SCR that has the anode connected to the tab. That's the input with the highest potential from ground!)
What I am asking is why in the world would they have designed it that way? These things even have a hole to screw it to a heat sink and you'd want the best contact to the heat sink, not layers of plastic in between.
Now I am certainly not the first one discovering that this is rather annoying. So why did the engineers so unanimously design things that way? Why not just leave it disconnected?