I think it's a matter of believing in the highest human potential, but realizing we haven't achieved it yet. "Wanting perfection" is putting on to the present moment the end product of uncovering our deepest human potential. "Working towards" is mixed with more realism, to understand "where we are at", and what we are working with, the person we are at this present time. Having compassion for who we are now, because we are not fully realized. If we are wanting perfection, it can bring in a lot of idealism, which can bring in a lot of rejection of who we are now. So there is a difference. There's a realization that to reach our inner potential, it's a path that we have walk to uncover that potential within ourselves.
Wanting perfection now is usually an expression of aversion towards what we see in ourselves. Aversion towards the Dukkha; aversion towards the Hindrances; aversion towards ourselves. Rejecting ourselves and racing towards an ideal of what we would like to be. So it's often bound up in self-hatred.
So if we have a lot of idealism it's important to remember that the Buddha was the ultimate idealist/perfectionist, but he was also a realist. He realized he had to work towards uncovering the truth and not expect it right now.
When we have compassion for ourselves we also have patience, acceptance of what is now, because we realize that that's the only way to let go. Being objective. Accepting what is present. Seeing its nature. That is letting go through insight. Seeing Dukkha, the cause of it, and through compassion for it letting it go.
As far as I understand, in order to be free, according to Theravadin Buddhism, we don't have to be perfect. Only a Buddha is perfect.