I might as well try my best to answer this question the best I know how, even given the insults in the question which points to an arrogance of which I won't concern myself. Why do people love Tali? I find the answer quite simple. Is it her bowed legs, or how you most insultingly put it "chicken feet"? No. Is it the mask? to an effect yes, but this is only to provide an air of mystery. Most of us can agree that the fact that her entire body is covered we cannot gauge beauty. And since we can't see her face we can't make assumptions to how she is like through that, so the player relies more on the personality aspect of Tali.
Now this is where what you assume to be a love affair. Most of the Talimancers can agree with me that the admiration and love for her character comes from how her character was represented. She holds the most positive traits of any other character in the game, showing personality and selfish desire to help her people, even if that means sacrificing herself to do so. Another excellent example of her selfishness comes from her desire to be with your character (if you pursue such) She tries to hide it and is nervously happy when you say that you still want to be with her. (This nervousness is also quite a cute action for a character to share showing more humanity (not in the species sense, but more so in the realistic sense than other characters.) Her personality traits are what writers strive to bring to their characters. We have a back-story that is touching and tragic. (Example: Her mother has died and her father didn't love her). Most people who love Shakespeare know the power of tragedy in developing a character. She is a tragic figure who still remains strong in her will to help others. Most of us "weirdos" actually prefer to find a woman with such personality traits. Not physical of which you seem so focused on.
Why do Talimancers jump at people who insult Tali? Well from my experience most of us don't, just more in the line of radicals while others strike more at the fact that it is a support thread and someone says negative comments in it, which don't belong if you are going to support them. So most times that Talimancers attack people for not liking Tali it is normally the result of Troll action in the thread. Now you only focus on Talimancers attacking people for their disapproval of Tali. I have had my fair share of attacks from Liaramancers for only having Liara get shot in my story, though I had no Talimancer attack me for when I burned more than 50% of her body and caused her to lose her hand. Mind you Liara survived. With this alone this debunks your thought that this is exclusively a Talimancer focus.
I might as well address the physical traits of her. Why do such people enjoy the "chicken feet" and masked face? For two simple reasons. 1) The chicken feet make her exotic and different from other characters, much like the Liaramancers enjoy Liara's head tentacles (sorry if this is an insulting statement to Liara fans), Garrus-mancers (if that is what they are called) love his head flanges and his mandibles, Jack's tattoos, Thane's gills(?), and Miranda's proportionally large rump. 2) As for the mask, like stated above, provides mystery and provides the gamer with an opportunity to express their imagination.
Basically we are given an amazing personality with a blank slate of physical appearance, which means, this woman could be any woman in real life as well. These personality traits are what makes her desirable so to look in real life for a Tali-like character it is simply to find a woman who shows selflessness and passion for what she puts her mind to, a will to make sure others are happy over herself, to not be a burden, and to never let go of those that she loves. All of which you can mostly agree with are positive and desirable in any character, male or female.
Any more questions, please ask and I will be sure to answer promptly.