This question is like asking can a quilt have too much blue? Everyone has their own feelings of what they like or don't like on just about everything, including quilts.
Heavy quilting in itself is a matter of opinion. I suppose the quilts I have posted here would be considered overquilted but I spend a great deal of time studying any quilt before it goes on my rack. I always try to acheive a look that compliments the piecing.
However, like Heather, I love the texture and the look. I am drawn to quilts where the quilting is that something that makes the piecing just shine. Or picks up on a motif in a fabric. I love the kind of stuff Green Fairy does, like that horse quilt with the compasses quilted, that to me was beyond beautiful but I suppose to others it was considered overdone.
I also think that business about a quilt becoming stiff as a board due to being to heavily quilted is hogwash. The batting is what causes the stiffness with heavy quilting. W&N is notorious for losing its drape when heavily quilted, so use a different batting.