The Yellow Line

Okay so can someone please tell me why metro feels the need to run four car yellow line trains during rush hour? The yellow line is the fastest way to get between DC and VA from the East side of the city, it runs from L'Enfant to the Pentagon two major stations moving millions of people from the Hill back home to the suburbs yet they run four car trains. Let me ask, who makes these fabulous decisions? Have they ever tried to cram into an already overstuffed train while the doors were closing on them? If they had I guarantee they would run six car trains only. It's ridiculous not to mention frustrating and annoying at the end of a long day. To be honest the city has outgrown any use of a four car train and Metro needs to give in already and add the other two cars and make us all happy, or at least happier.