Indeed: motive, rather than action, is the informing factor in most cases - alignment isn't so much about what you do, as why you're choosing to do it. I do have to admit, though - that's a much more nebulous thing to pin down in a video game context, and that's the main reason, I think, why we always end up falling back on ascribing alignment to specific actions and disregarding the motive or reasoning behind it, in video games - the game can't track our reasoning, in most cases, so it ascribes a motive to you and judges you based on that... often to the detriment of immersion, sadly.
I think this is why I have a hard time with it in video games as well. The "good" path usually means being a doormat and the "evil" path means being an idiot. It gets really frustrating.
