Yup, I wore a blue calf-length bridesmaids dress because I knew, from going to one or two formal events, that I just can't move well in a full-length gown and would just look uncomfortable, plus I'm only just over 5ft and, I'm sorry, but I think if you're short, big, long skirts make you look like you're melting into the ground! 
Also it was a wedding in a barn, I thought a big dress would be OTT
and might get muddy (in the end it poured on the day).
One note: I had no bridesmaids, just a flower girl and I think my dress, not being white, might have risked it not being clear who was the bride if I'd had adult BM party (that wasn't the reason I didn't have them, btw, there just weren't any obvious candidates!), so just be aware of that.
Screw it 'not being glam enough', it can be as glam as you want, it's all in how you wear it, there's no need to be 'worn' by a big dress.