It is a social/ethical issue. A pattern or technique can NOT be copyrighted. What is copyrighted is the wording, illustrations, etc. of the pattern, but not the pattern itself.
I wouldn't feel right copying someone's ORIGINAL work...and by "original" I mean something that is not comprised of blocks that are ages old...or a twist on those older patterns achieved with color or fabrics...
~shrug~ My two cents worth, for what two cents is worth these days! ;)