Why? Isn't it dangerous? (sarcasm) ... Just as you said a semi-automatic pistol is dangerous if a round is in the chamber.
And, if you have an older, single action revolver without a transfer bar, all chambers loaded, with a live round under the hammer, a revolver drop to the hammer could cause it to fire.
And yes, I always treat my Hi-Power and MKII differently than my GP100.
Always makes storage interesting because pistol boxes and bags are not big enough — always store both with the slide/chamber open.
Not that easy in a holster, either.