Another way to look at things, instead of thinking about a "matter-of-fact" way of delivering knowledge, is to look at an instructional pro as someone who does indeed have a lot of experience, garnered over a very long period of time, who has done and tried a LOT of ways of doing things, and has a very firm grasp of what works and what does not.
Here is an example. I love Art Morris' bird photography. The insight and knowledge he FREELY disseminates on his blog and on some bird photography forums is utterly invaluable. His delivery method is blunt, directly to the point, matter of fact, and often somewhat shocking or startling in it's delivery. However, I don't complain about that. The guy has been doing bird photography for longer than I've been alive. He KNOWS what he is doing, he KNOWS his stuff, and every time I listen to what he has to say...regardless of his method of delivery...I learn something, something invaluable, something that improves my skill and changes my photography.
If all you ever do is look at the method of delivery, you miss what's being delivered. I think Art Morris could be a little less blunt in the way he delivers his insight, but I honestly don't care that he's blunt and direct...THE GUY KNOWS HIS S___!!! The fact that he freely shares his knowledge is amazing, and I'm a better photographer for it. If/when I scrounge up the $12,000 or so for one of his IPTs, I'm going, I have no doubt in my mind that it would be some of the best $12,000 I'll ever spend. And to be quite frank, I would rather have someone shut me down when my own thought processes are going down the wrong path, and correct my understanding of a concept or theory immediately, than allow me to continue thinking about something incorrectly. By allowing me to keep my own incorrectly formed opinion, they aren't doing me any good, and rather could be doing me a disservice. You learn from your mistakes, no? Well, you have to know what your mistakes are first, before you can learn from them.
Sometimes what may seem like arrogance may simply be the consequence of having a great depth of knowledge. It isn't arrogance or rigidness and a lack of willingness to change one's opinions. It's a confidence that one's opinions are most probably right, a confidence backed up by years or even decades of extensive first-hand experience, and justification to put the burden on the other guy
to prove them wrong. Granted, there are exceptions to the rule, but those exceptions usually tend to out themselves quick enough, with either too much arrogance or not enough knowledge...ignore the exceptions, listen to the experts.
As much as I think I may know something, if it's Morris or Murphy or any number of other highly seasoned bird photographers, or Andy Rouse or other world-renown wildlife photographers, or one of the juggernauts of astrophotography like Robert Gendler or Russel Croman, I bury my own opinions, shut the hell up, and let them teach me. ;-) As a small example, I thought I understood exposure. Then I bought and read Art Morris' book "The Art of Bird Photography", and learned not only that I knew nothing about exposure...but I also LEARNED
Anyway...thought that needed to be said, in general, for anyone who would listen.