First let me say I usually always get my steaks medium rare.
However I do not think that a burger cooked medium rare is the same as a steak, because the meat is generally not even close to as good a quality. Also, On a burger, I actually like to have a little bit of texture and bite, and when I'm chewing on a medium rare burger, I have a hard time even tasting the meat and it's kind of mushy. Burger's generally have a high fat content in the meat anyway, so it's not like it's losing a lot of the juiciness when it is cooked medium or medium well, atleast in my opinion.
Am I missing something here? The only time I'm ordering a burger medium rare is if its Kobe or super high quality.