I am sure that it is at least on equal terms merit of the actor himself and the film crew. No other character in those movies is even close in terms of how interesting and stylish there clothing is. Maybe he was supposed to be the "stylish, cool looking" character. But, bad guys are also often supposed to look stylish and cool so that they are more of a challenge for the good guys. And there is not one movie where anyone would be even close to Terence Hill in terms of stylish clothing.
Indeed it is rarely seen in any movie, that a main character would have such a fabulous unique and sophisticated style.
I am posting some pictures (not the best quality, will improve when I get my hands on better) to prove my point:
