I was more looking for what is meant by IDEALISM as a term. There are many types of idealism.
Noun 1. idealism - (philosophy) the philosophical theory that ideas are the only reality
philosophy - the rational investigation of questions about existence and knowledge and ethics
philosophical doctrine, philosophical theory - a doctrine accepted by adherents to a philosophy
2. idealism - impracticality by virtue of thinking of things in their ideal form rather than as they really are
impracticality - concerned with theoretical possibilities rather than actual use
romanticism - impractical romantic ideals and attitudes
knight errantry, quixotism - quixotic (romantic and impractical) behavior
3. idealism - elevated ideals or conduct; the quality of believing that ideals should be pursued
high-mindedness, noble-mindedness
magnanimousness, nobleness, grandeur, nobility - the quality of elevation of mind and exaltation of character or ideals or conduct
http://www.thefreedictionary.com/idealism
What at first caught my attention was that the in the OP the question was loaded with the presumption that the "best" form of idealism is staying true to your ideals derived from Fi type feeling, when there are other types of idealism and different manifestations of idealism, like the ENFJs social idealism, for example my friend wanting to develop psychological coping techniques for people with mental issues, or like my ENFP husband who actively lives a very engaging life according to his own value principles and my INFJ way: Having had a series of Ni type epiphanies about life, universe and everything I would be a philosophical idealist. It is apparent in my creative work. Same way I'm sure INFPs mold their lives according to their unique values. I just personally don't think there's anything better about any of the ways, they're just different ways.
I personally think EVERYONE plays an important part in society, the idealist as well as the accountant and salesguy.
I'm the better equipped for one thing while some other type is better for another.
And as for popular opinion, I don't much care about it. It's just a matter of taste. I've got mine, other's got theirs. Who cares? Whatever matters to other's doesn't have to matter to me. I don't much bother with that stuff. Most things I've worried about, how others would feel about them, well...I've only pestered myself. The trick how to be free of that is to stop worrying about what others think, what they like or what they don't like, respectfully. You don't have to care if your views are not popular.
As for trying to convince people to "do the right thing"... that never works. Say your peace but don't have expectations about it having any impact. Everybody has to deal with their own head. People hear what they want to hear. If they want to hear "Let's be in peace" they'll be listening for it. If not, they'll not hear it even if you stand on a soapbox with a megaphone. And to be honest many idealistic people use "the truth" or moralizing a bit like a weapon to ridicule others and strip them of their cherished beliefs rather than as something used out of love and concern for someone else's wellbeing.
We work on ourselves in order to help others,
but also we help others in order to work on ourselves.
Pema Chodron