You can find creative gamers in all gaming niches, but I think that boardgames tend to offer you a “closed” gaming setup, as where miniature games more often offer an “open” gaming engine.
I think much has to do with the way in which both types of games are marketed. Boardgames have everything in the box – there is no need for tinkering. But a typical miniature wargame doesn’t even come with a gaming board. That also implies that miniature wargaming rules tend to be more flexible to cater for a lot of different situations, and that leads to a larger tendency for using house rules, modifications, proxies for miniatures or scenery, inventing your own scenearios etc. The rules also require you to be more flexible. A rule like line-of-sight will always need some improvisation in a miniature game, but in a traditional hex-and-counter wargame, LOS is usually very precisely defined.
I rarely see house rules being used in boardgames. But I see houserules in miniature gaming all the time. And the same creativity applies to scenarios.
Tiny Tin Men Blog: http://snv-ttm.blogspot.com/
Wargaming Mechanics Blog: http://wargaming-mechanics.blogspot.com/