I'm a 4th yr med student with admissions experience.
It is important if you were economically or educationally disadvantaged growing up to include it in your application. Most schools have a way for you to include it--extra essay for example.
Your accomplishments should be measured not on an absolute scale, but relative to what you had to begin with. If you had to work to support your family, are the first in your family to go to college or grew up in a crime ridden impoverished neighborhood, it will affect your academic performance and casts a whole different light on your record.
If you grew up impoverished and had no educational opportunities, it may be a huge accomplishment just to get to college, stay in college for example. It's downright humbling when I think about some of the stories I've heard.
People who work 40 hours a week and go to school FT have a harder time maintaining a 4.0, doing research, volunteering, or becoming an elite triathlete and likely can't take the summer off to save orphans in Romania. Also, the quality of your HS predicts your initial performance in college.
Even though AA is officially banned, these factors are (and should be) considered. The medical profession is not reflective of the general US population (in race/ethnicity or SES) even more than 30 years after the civil rights movement. A growing body of evidence shows disparities in health and suggest disparities in quality of care for nonwhite and low SES patients.
It's important to have better representation of the general population in the medical profession--not only to provide opportunities for certain students and the care of certain patients, but to enhance the training of ALL docs and ALL patients.
If you are actually disadvantaged, feel free to pm me for more advice.