As religions go, Judaism tends to be practical and avoids extreme asceticism, at least for the uninitiated. Even though marriage is not only about physical and sexual gratification, Judaism does not ignore the basic sensual and physical needs necessary to form and maintain a loving bond. 

Amud Beis discusses marrying and then later discovering a deal breaking blemish. While we are on this topic, Akeidas Yitschok (Chayei Sarah 16) asks a series of questions regarding Yitschok’s Shidduch process. We know that it is forbidden to marry a woman without first seeing her (Kiddushin 41a). If so, how could Yitschok marry Rivkah (according to those who hold that Eliezer was a shaliach kiddushin, and actually enacted the marriage via the giving of the bracelet (Bereishis 24:22)?  The Noda BeYehuda (EH:I:77) also grapples with this question and offers two answers:  It is permitted to use a shaliach when there is no choice, and Yitschok was not given sanction by God to leave Eretz Yisrael, so he had no choice but to use Eliezer as his shaliach.  Also, the reason why it is forbidden to marry a woman sight unseen, as that he may discover a blemish and then invalidate the marriage (as our Gemara has been discussing).  Therefore, if the person takes it to heart that he will accept any and all blemishes, then it is not an issue.  Akeidas Yitschok does not accept this answer, as he says, how can a person really know which blemishes they can tolerate?  Indeed, the Gemara later on (77a) discusses a scenario where a woman even says she can tolerate a certain blemish but then, after marriage, realizes it is too much.  

Therefore, Akeidas Yitschok offers a different explanation. We are taught that Avraham did not even notice Sarah’s beauty (Bava Basra 16a, Rashi Chumash Bereishis 12:11).  If a person is on such a level that he plans never to see his wife and evaluate her as an object of beauty, then such a person can marry sight unseen.  If this was Avraham’s middah, we can assume it was Yitschok’s middah as well.  He also relates a story from the Gemara (Shabbos 53b) about a man who was married to a woman who was missing an arm and did not realize it his entire life! 

Of course, no one should attempt to live with such a high standard as to ignore looks entirely. In fact the simple implication of the Gemara in Kiddushin is that it is ill-advised, and even forbidden to ignore basics such as attractiveness (depending if you follow the Noda BeYehuda above or side with the Akeidas Yitschok.) 

However, if there is no lesson in these stories, why do the rabbis tell them to us at all? I believe the answer is to remind us that there are matters of greater importance than mere looks.  Though one should seek a spouse whom he or she finds attractive, and each spouse should continue to maintain and not neglect their appearance, over time of course it is inevitable that different aspects of appearance change as the body ages.  Once we have chosen our mate, we must find ways to find them beautiful for who they are and overlook any flaws.