I'm curious about where the 'negative numbers optionally converted to bonus damage' comes from- I can't find a reference to that anywhere. Was this maybe a house rule you guys used?
Is it not in an optional rule right under the fighter hit table in your PHB?
"...the negative score may be converted to a positive and applied as additional damage to the automatic hit. Thus,
for example, a 20th level fighter with 19 strength and a +5 sword attacking an AC 2 dragon would require a roll of -8 to hit it; the character would be allowed to modify his or her damage roll by +8."
Given the paucity of decent argumentation skills I see in forums that should demand it in meatspace, color me unconvinced that the level of discourse improves on the internet. Well, that and personal experience since 1991 (MUDs for the win!).
Besides, I am not a big fan of the bus driver's holiday.
No offense, but that looks as dismissive as some of the comments you were arguing against. The level of debating skill isn't the point. It's the activity to increase that level of skill and a demonstration that your point 2 above is just as possible on the internet as it is in person. There are people on the internet who are open to real discussions too.
A person cannot say "because these people did not" means "these other people cannot". That's an example of a biased perspective applying the traits of one group to the other without justification.