I've said it elsewhere and I'll say it here. Tali DESERVES a face. Its not a matter of fulfilling someone's fantasy, or what have you. A character is someone's projection of emotion, motivation, personality, and appearance. The character has a right to be understood by anyone experiencing them, and the creator of the character has a right to unveil the character in the exact way they see them. It was like Darth Vader in Star Wars. As a villain he was represented by the cold, dark mask as a shadow of his former self. But when he returned to the man he was, he needed that face. This is in opposition to a character like, say, V from V for Vendetta because his mask did represent the man who he was throughout. This is the difference between a static and a dynamic character. Vader changes over the course of the story, while V does not. When Shepard shows his feeling for Tali, it changes her. Not in the sense of who she is, perhaps, but in the sense of replacing her mystique/aloofness with tenderness and trust. And the transference takes place fine, coming to climax in the love scene. When Shepard sees her face, there is no longer a mystery for him, as it has been replaced with affection. That is what the player should feel as well. The mystery served well, perhaps, in drawing some folks in. But the rest of the story doesn't hinge on that, because Shepard knows what he sees, and presumably he likes it.
This isn't to say I'm unhappy with how they handled it. I felt like this was the developers playing a joke on us. And I thought it was funny, in a twisted evil sort of way. They got to have their fun at our expense. Now they owe her, and us, a real face.