I personally believe that every Trans, wether they want to admit it or not, has a certain level of characteristics from the desired sex that they want to obtain before they can walk out into public with sanity and confidence still attached - that is, unless they actually take pride in appearing strange or contradictory, something that some Trans do take pride in for sexual, personal, or religious reasons. In this day and age though, harassment, discrimination, and fear cause most Trans to still want to be passable at least to the "confusing" level, a point where strangers at least have to do a double-take, or at least where people do not point and laugh. I believe most of the Trans out there do want to eventually be confused for the sex they want to be, even eventually being always taken for the chosen gender. Many also want to be seen as handsome or pretty, two descriptions that make up some of the most important romantic emotions in sexual identities themselves.
Wether this level of characteristics is simply a wig, dress, and heels, or reaches farther into both facial and body surgery or hormonal changes, every Transperson obviously partakes in some sort of physical change, and every Trans obviously has a different level of innate passability concerning physical features. As in the psychiatry of 'normal people', the importance of appearance to a human being directly involves a person's history of trauma, current sociological age and society, and family-career surroundings, all of which are things that are no less important than the identity of being Transsexual. The simple facts are that most people want to wake up in the morning and see the person they are on the inside represented on the outside. Where as "normal people" live a constant merging of soul and appearance (and thus, with ease, feel that their body and face well-represents their soul), Trans-people live a lifestyle where, because of the way native hormones work, the soul divides with the body's growth and appearance every day the person is living; that is, until they get hormone therapy or various surgeries, many of which many Trans can't afford.
A Transperson usually wants to pass for many reasons; my personal reasons are that, in my age group, trans who do not pass are constantly bullied and threatened, that in my age group, trans who do not pass are not considered physically attractive even by Trans-friendly people and potential partners, and that I simply feel suicidal and depressed if I cannot start my day passing, or at least encompassing in a personal way, the gender I prefer. As my face and body continue to age (balding, hair grown, facial structure, ect ect), the strength to do this has all but vanished and I, for some time now, have been literally forced by my emotions and physical defects to live as the man my body wanted me to be. I still try to socialize with people my own age (early 20's) and simply no one my age, not even the most trans-friendly person, can "see" a balding, hairy male as female, no matter how hard they try.