Well, the question is this:

Don't you already know what your partner finds unattractive about you?

For the vast majority of people, the answer to that question is yes. So that leads us to the followup question:

Given that you have less-attractive qualities (because we all do) and given that you know what they are and that you know that your partner knows what they are, which is going to lead to a better relationship?

One where you can speak honestly about those things, or one where you are agreeing to lie about them?

For some people, sure, the answer is "lie." We're going to pretend that we're 100% attracted to everything about our partner all the time.

But for some people, that lie is insidious, because it creates doubt in all sorts of other aspects of their relationships. How can you trust them when they talk about your good qualities if you know they'll lie to your face about your bad ones? Maybe they're lying about you looking good in that dress because they sure are lying about not being bothered by that big hairy mole on your lip.

Pretty much everyone who does a workshop of this sort comes away with the same experience: they feel closer to the people who just, compassionately and lovingly, told them the truth, even if the truth itself was painful. If you do a dyad with a stranger you'll often find yourself making a new friend. If you do it with a partner you'll often find your relationship strengthened.

It can be a very powerful experience to hear someone say, "That thing you're self-conscious about? I see it. I'm not crazy about it. But I find your beautiful anyway." It's certainly more powerful that them pretending they don't see that thing which you know they see.