if hackle represents legs, why do we use anything but black and brown and grizzly?

[Silver Creek]

When you say variant dry fly style, do you mean kind of long and sparse? If you tie the hackle this way, do you add a feather wing, or not use any material to represent the wings except the long hackle?

A variant would have longer palmered hackle and usually absent a separate wing.

See these examples:

http://www.orvis.com/store/product.aspx?pf_id=90KH

http://www.flyofthemonthclub.com/sto....asp?item=1206