StingingVelvet: I think if you took an RPG and removed all combat mechanics it would inherently become an adventure game.
I would disagree. I think the basic structure of an RPG is character development within the role you have chosen to play and story telling. I do not think that combat is a necessary component. You could make an RPG about being a merchant, or an explorer, or even a scientist and tell a good story and develop an interesting player character without combat.
Aaron86: I'm not sure how much gameplay there'd be in an RPG that's neither combat based (be it strategic or twitchy) nor basic adventure (cruise around the world, collecting things and clicking through dialog trees).
I suppose there's the stat management. Though the thing is combat often lends itself to emergent situations due to how much of a simulation it usually is. That's why you can have random encounters and roguelikes where the combat will still be somewhat interesting.
Non-combat uses for stats in RPGs are either piddling things like cheaper prices in shops or pre-scripted binary checks in you'd never know about unless you've read about it in a walkthrough.
I think adventure is an important part of any RPG (no one would what to role play my life as an office drone). And adventure needs conflict. But most RPGs go for the adventure through combat as opposed to so many other types of equally interesting types conflict such as intrigue, economic competition, romance, etc.