I would like to advocate for the potential power of Fi and try to explain its inner workings. I highly recommend Lenore Thomson's Personality Type in this regard.
Fi seeks universal values. "Respect all life" is a good example. Such universal values transcend both oneself and one's culture. Also, being universal in their nature we don't need to ask other people if they agree or whatever [Fidelia, you asked about Fi needing others approvals like Fe does, or however you phrased that]. I don't need to go ask Suzy "Hey, I was wondering, 'respect all life', you think that's a good idea? No, yeah me either. So anyways I like your blouse!" Nor do we say "respect all life. Well, except for people taller than 6'2", or all life except for people with green eyes cuz we know that they just don't count." That's not universal enough. If Suzy disagrees with my "respect all life" value, I'll just think she's not particularly highly-morally-developed. But I don't think that I'm wrong because she's thinks I'm wrong, or even because my culture says I'm wrong.
Where Fi gets tricky is each owner has their own personal values. What applies to me may not apply to Blackcat for example, and vice versa. Also, some INFP's Fi values may be very unrealistic "We should all sit in flower-filled meadows and dance and sing and write love poetry, screw capitolism you selfish bastards!" comes to mind as an example. Also, authenticity is very important to Fi. I can't stand here and say "Respect all life" and then be like "I'm bored, I'm going to go run over a cat with a lawn mower", thats not being authentic to "respect all life". Note: An INTJ classmate described engaging in such behavior to me, it earned him instant asshole/moral-scum status in my mind.
Also, it can be VERY hard for us to pinpoint our Fi valuers, or else saying them just sounds, I don't know, odd or obvious or unilluminating or whatnot. "Its important to be a good person because it is", not really to helpful or informative or explanational huh?
The potential mega-strength of Fi: The ability to have very evolved universal values that "lead the pack". Think "all adults should have the right to vote" leading to womens suffrage for example. "Treat all people with respect" "No one is beyond redemption", developing humanistic psychology and helping people to "achieve their full potential". The deepest levels of compassion for other people arise from the INF's. I'm not going to try to claim that Gandhi or Dr. Martin Luther King Jr. were INFP's, but focus on how they took a value or idea and "fought" for it non-violently and changed the world in the process. High emotional/moral/ethical development and manifesting it into the world. That is what we can bring to the table. Especially our "warrior" INF's, or those willing to "fight" for their values.