If you are out of college for a few years, work full-time, and took pre-reqs at night, please explain how going back to your alma mater 500 miles away and interviewing with people you don't know and who don't know you will be a good use of anybody's time?
Committee letters are just a way for schools to lower the risk of accepting a 20 year old. They could be getting a very mature student with a strong work ethic. Or they could be getting somebody who doesn't know how to write a check and who's mom orders dinner for him every night and makes sure he is doing his homework and not playing video games. Once you've been out and held a job for a few years and you've got a resume of actual work experience to vouch for the fact that you're an adult, you don't need a standardized committee to prove it anymore.