nah, try it and see. your mids just give a specific contour to your overall sound. all mids and nothing else... well, it doesnt sound all that pretty. but that goes the same for all bass and nothing else, or all treble and nothing else.
me personally, my distortion channel settings go like this: lows on 6, mids on 3.5, highs on 8.5.
on one thread that I cant find at the moment, Lats went in detail about how to get a good clean tone. you basically start all your settings at the uneffected level (it differs from amp to amp, but try on 5.) and just start with one, like bass, and play with it till you like what you hear. leave a bit, let your ears get chilled out, then come back and play with the next level, and so on. you just fine tune it till you like what you hear. it may take days, but its worth it.
I did the same thing with my distortion channel too. it is different from my clean tone, mind you.
some songs, ill dial in more mid to get more punch, some more bass for more rumble. you get the picture.
-Agile Guitars Enthusiast