It's funny you say that, because I was thinking about what Van Halen would sound like if they were produced by Mutt Lange. Too be honest, I actually think it'd sound pretty horrific. 5150-on was already pretty slickly produced, and I'm sure Mutt's sound would make Van Hagar sound pretty artificial, and the fanbase would've just left in disgust. Hell, people were spitting-mad about keyboards when 1984 came out.
Guns n' Roses Illusions albums were already over-produced, and we know what happened with that.
RATT was produced by Beau Hill, and considering Beau Hill was the 'Timbaland' of hair metal, I think RATT sounds just fine without any more processing.