What is the theme of "The Furnished Room" by O. Henry?

The theme of "The Furnished Room" is that New York is a cold, heartless city that devours people and destroys their dreams. Many people are drawn here because it is possible to achieve spectacular success, as Carrie Meeber does, for example, in Theodore Dreiser's great novel Sister Carrie. But the majority of people with artistic talents of one kind or another find that the competition is overwhelming. They get worn out with living in the horrible conditions described by O. Henry when the young man follows the housekeeper up the stairs and into the furnished room. Such rooms seem designed to create despair. They get discouraged by all the running around they have to do trying to find a little paying work, whether it be in acting, singing, dancing, writing, drawing, or whatever else. Johnsy and her friend Sue are both good examples of aspiring artists in O. Henry's story "The Last Leaf." Sue is struggling desperately to make living expenses by doing sketches "on spec" for some magazine. Johnsy has given up the struggle and is only waiting to die. The girl the young man is searching for in "The Furnished Room," whose name is Miss Eloise Vashner, came to New York with high hopes, but she gave up just a week ago and committed suicide by the then standard means of turning on the gas without lighting it.

The furnished room in the story is beautifully described in all its ugliness. It symbolizes the lives of the many aspirants who come and go--

Homeless, they have a hundred homes. They flit from furnished room to furnished room, transients forever—transients in abode, transients in heart and mind. 

This rooming house is the end of the line. You can't get any lower than that. And when a person moved into one of these gritty, smelly rooms, it is a good indication that suicide may be the next step down. 

It would seem that Eloise Vashner had enough talent to make her ambition plausible. When the two housekeepers are talking about her at the end of the story:

“She'd a-been called handsome, as you say,” said Mrs. Purdy, assenting but critical, “but for that mole she had a-growin' by her left eyebrow. Do fill up your glass again, Mrs. McCool.”

The mole serves a dual purpose. It identifies her positively as the girl the young man had been seeking. It is also a tiny defect that may have been responsible for her inability to succeed in her chosen career as an entertainer. The competition in show business is so fierce that anything short of perfection is a nearly insurmountable handicap. Today there are countless thousands of talented people, including beautiful girls from every corner of America, flocking to New York and Hollywood with nothing but youth and hopes. They will find that the competition exceeds their worst expectations. 

Another related theme in "The Furnished Room" is that Eloise Vashner should have stayed in whatever small town she came from, married this young man who so obviously loved her, and settled for a simple life in a little house with a family, a rose garden, and some friendly neighbors.