You are not wrong of course, but on the scale between "between blindness towards biases, and ignoring human nature" your views fall 80%-90% towards "ignoring human nature".
Just to give you a more complete image, here's a thought:
People are not consequentialists, and they don't know clearly what they want.
In fact, there is nothing "absolute" that tells us what we "should" want.
And the happier you make people, the happier they tend to be with the goals you give them to work on.
If you also teach people rationality, you will get more scrutiny of your goals, but you will never get 100% scrutiny. As a human, you are never allowed to fully know what your goals are.
Looking at the "human nature" side, people who "care deeply" about EA-style things are just people who were in the right situation to "unpack" their motivations in a direction that is more self-consistent than average, not people who fundamentally had different motivations.
So my "human nature" side of this argument says: you can attract people who are in it "just for feeling good", give them opportunity to grow and unpack their inner motivations, and you'll end up with people who "care deeply" about your cause.
I was invited by a stranger I met on a plane and actually went to a meeting of Raëlians (known in some LW circles as "the flying saucer cult") in 沖縄, Japan. It was right next to Claude Vorilhon's home, and he came himself for the "ceremony" (?) dressed in a theatrical space-y white uniform, complete with a Jewish-style white cap on his head. When saying his "sermon" (?) he spoke in English and his words were translated into Japanese for the benefit of those who didn't understand. And yes, it's true he talked with me briefly and then hugged me (I understand he does this with all newcomers, and it felt 100% fake to me). I then went on to eat lunch in an 居酒屋 with a group of around 15 members, who were all really friendly and pleasant people. I was actually treated to lunch by them, and afterwards someone gave me a ~20 minute ride to the town I wanted to be in, despite knowing they won't see me ever again.
If you have ever wondered how it is possible that a flying saucer cult has more members than EA, now it's time to learn something.
Note: I hope it's clear that I do not endorse creating cults, nor do I proclaim the EA community's inferiority. It hasn't even crossed my mind when I wrote the above line that any LW'er would take it as a stab they need to defend against. I'm merely pointing to the fact that we can learn from anything, whether it's good or bad, and encouraging a fresh discussion on this after I gathered some new data.
Let's do this as a Q&A session (I'm at work now so I can't write a long post).
Please ask questions in comments.