Well, I think the reason why INTJs tend to naturally gain more respect is because they come across as role-models, being so confident in themselves and rarely showing self-weakness.
INTJs have an uncanny ability to rise above stereotyping; thus it doesn't effect them. This is a distinct strength that makes you folk stand out. My INTJ friend wouldn't give a rat's ass what anyone thought about him unless HE valued them to begin with.
I think that is a natural-born wisdom you INTJs possess, making you the beacons that attract the rest of society.
Other types will constantly see you and ask, "Why is he so confident, even in the face of mass opposition? I wish I knew myself that well; believed in myself as much to display that kind of courage."
Therein lies the secret, I think. My INTJ friend was hilarious as hell whenever someone misjudged him. His favorite saying seemed to be,
"Whatever, dawg. I really don't give a shit." What made it so funny was the tone he carried while saying it. It always had a hint of laughter in it.
Now, whenever close friends would confront him with a problem, he would be the best of listeners, and always take what we said to heart.
INTJs know where to place their trust, which is perhaps another reason why they get so much respect.
Also, your straight-fowardness is probably just what your INFP friend needs, especially if he thinks you are trying to insult him. INFPs have a natural tendency to take criticism personally rather than objectively. They all need to overcome this, or their emotions will go crazy and become difficult to control.
I call it the classic case of INFP paranoia, due to insecurity and a skewed longing for peace and perfection in all things.
Applying logical interpretation to criticism will do tremendous wonders for your INFP friend.