Dear Noson,
Your denial of "that beauty plays a role in either physics or mathematics" strongly contradicts to the history of fundamental science, from Kepler and Newton to Einstein and Dirac. Your quotation of Einstein is an example of an extreme misinterpretation by taking out of context. The only reliable source where I know Einstein mentions this 'tailor' comparison is his preface to "Relativity: The Special and General Theory" (1920). His words follow:
"In the interest of clearness, it appeared to me inevitable that I should repeat myself frequently, without paying the slightest attention to the elegance of the presentation. I adhered scrupulously to the precept of that brilliant theoretical physicist, L. Boltzmann, according to whom matters of elegance ought to be left to the tailor and to the cobbler."
I suppose that it is perfectly clear that the specific elegance left here by Einstein "to the tailor and to the cobbler" has nothing to do with neglect of the mathematical elegance or beauty. It is hard to say anything further from truth than to claim aesthetic negligence of Einstein in general and in the matters of theoretical science in particular. There are many clear statements of Einstein about the role beauty played in his own thought and in the history of science. Take for instance the following, where Einstein defines mathematical beauty, or "inner perfection" of theory:
"Pure mathematics is, in its way, the poetry of logical ideas. One seeks the most general ideas of operation which will bring together in simple, logical and unified form the largest possible circle of formal relationships. In this effort toward logical beauty spiritual formulas are discovered necessary for the deeper penetration into the laws of nature." (Obituary for Emmy Noether (1935))
Thus, mathematical beauty/elegance is a unity of logical simplicity and richness of the content. In one or another way belief in the elegance of the laws of nature was expressed by many fathers of science, and this belief played a crucial role in the history of science. When Wigner wrote about 'unreasonable effectiveness of mathematics' he did not mean that laws of nature are somehow described by formulas; he meant that these formulas are both simple in form and rich in content.
The actual question, missed by many essays of this contest, including yours, is why 'the laws of nature are expressed by beautiful equations', as Wigner's brother-in-law put it. Symmetry is just a part of this logical simplicity. We may imagine a universe in which laws have nothing to do with any sort of symmetry and can be described by kilometer-long formulas only. Why the laws of our universe are so symmetric and so simple, which made them discoverable? This is the real question meant by Wigner, which your essay and so many essays here have completely lost.