I've asked myself that recently. When I identified as male, I wore tattered & faded black jeans until they got too torn in the crotch to wear in public; the same black fleece vest every day, and various drab-colored t-shirts. Same exact outfit every day, for over 15 years. The pants and vest were washed when I could smell 'em from across the room. Well, a few days after that point, actually, because it took me a while to get around to things. But dressing feminine, for me, means not dressing like a slob all the time.
Additionally, I'm starting a new job soon, and I'm planning to aim for "dyke" so that I can pass as male but still feel femme. So I asked myself: could I be happy just wearing nicer guy clothes? I didn't think the answer would be yes, so I didn't try hard.
Last week i was trying to put together an outfit. I was in boymode, and I had to go to a department christmas party on the same day that I had to speak in front of a bunch of high school kids. I wanted to wear something that would be appropriate for both events, and despite being in boymode, I desperately wanted my outfit to resonate with any gender nonconforming youth in the crowd. Figuring out my outfit took quite a bit of trial and error.
In playing dress-up, I accidentally stumbled on a very sexy guy outfit -- the kind only straight Persian men can pull off... not even gay guys feel comfortable looking this good. The gears started turning... and I asked my boy self "would you ever wear this?" And he was like "um... can I have my vest back? It still smells about the same..." Eventually, I decided that this sexy man should take my wife out on a date, even if it makes me feel a little uncomfortable. After all, I've grown accustomed to finding myself dressed too feminine or too masculine partway through the day. She knows that the outfit would be a special occasion and not "the new me" or something. It's just another outfit I can have fun with.
To dress like a stylin' dude all the time? No. Absolutely not. I can't be happy just as a good-looking guy. Explicit femininity is necessary.