Q: Why don’t we have any idea of what Rebbe Nachman Zatzal looked like?
http://www.breslov.org/comment-on-the-reputed-portrait-of-rebbe-nachman-of-breslov-z%E2%80%9Dl/ where Ozer Bergman discusses this.
There were certain physical features we know about him, such as that he had red hair, was tall and that he had a short beard, he certainly didn’t look like what some people would require todays 21st Century Rebbe’s to look like.
In a similar vain to what Ozer has already written, perhaps it was not the physical features of the Rebbe that Rebbe Nosson and/or the Rebbe himself wanted us be preoccupied with. Perhaps it was the message that the Rebbe correctly predicted would burn until the coming of Mashiach that we are to strive to live with. This “intangible” image of the Rebbe would be color blind and could transcend all physical or other type of barriers which human beings are so apt to create. It would also prevent anyone from making an “Avoda Zara” or idol out of the physical appearance of the Rebbe which automatically forces people to attach themselves to the pnemiyut or essence rather than a relationship based on physical features.