Yes it is, in a way. You're evaluated by several people besides your own instructors and some of those pre-health committees interview you, so it's a good thing to go through. Adcoms do value committee letters, however not everyone can get a committee letter so the individual letter will do.
The really important thing is that committees tend to put together your best attributes from your letters and write you an ultimately the best letter which is a composite of all the individual letters. The risk of submitting all individual letters is that you may end up getting a rather generic and boring letter which happens more often than not,like "Student ____ was a good student. Got an A in the class. I recommend her" type of thing. My pre-health advisor has received 3 liner recommendation letters. That could be very very bad.