What is the reason that an off-hand attack does not include the ability modifier to damage?

Peroanally, it would seem that you could still hit as hard, and the penalty should be for the roll to hit, not the damage roll.

— JT G (@Gwozdzilla) April 17, 2020

I was referring to the two-weapon bonus action, and thank you for a great answer! Thinking of it as a “quick” strike makes perfect sense. You're welcome!

— Jeremy Crawford (@JeremyECrawford) April 17, 2020