i think it adds to it for the reasons stated already...but i agree, you don't need to tune lower to have a heavy sound. it just takes more writing ability.(edit: i mean to write something really heavy but in standard e)

i do think you can definetly go too low though...i haven't really tried playing anything below b, but i don't really want to. strings are so damn loose.

since everyones been going on about it...i am usually in b myself..but change tuning all the time. depends on what i'm playing.