I'd bet good money that it was Peter Jackson himself. In the LOTR his makeup guys knew he wanted that one 'John Wayne' Orc to be gruesome, and they actually tried to overshoot what Peter Jackson expected. Little did they know that Peter Jackson of "Dead Alive (Braindead)" fame was still alive inside Big Budget PJ. He approved it. Since then, you have seen the costumes for the grotesques go beyond the realms of good taste and into comically aweful. Just look at how the orc costumes changed from Fellowship to The Hobbit (before they went CGI), the Hobbit 'main-bad' orc costumes were so far over the top that they had to ditch them for CGI because they looked horrible with the higher framerate/quality cameras BBPJ was using. Personally I think the only reason people think the costumes were awesome was because the CGI was so bad.
Seriously, take a side by side look at LOTR-Lurtz and the Hobbit-Orc costumes and it's night and day.