I don't want to go off on a tangent about what makes a story good and whose opinion matters. I want to focus on what plot really is and why I think the distinction above misses the mark most of the time. Plot is not simply the happenings in a story. It's not the action or events. For me, plot is conflict; the interruption of the storyline.
Conflict need not be big and broad. Sure, the bomb planted in the building and our hero's race to find and diffuse it is big-time conflict. But a knock on the door is conflict. It changes the storyline - the room is no longer silent, our protagonist no longer alone, and a mystery awaits on the other side of the door. There's a choice to respond to the knock or not, to call out or to look out the peephole, to leave with the newcomer or turn them away.
Whether you hope to make a book a page-turner by having lots of action and suspense, or you want to delve deep into your character's psyche and unravel the mysteries of life, you need to have change and development. Every new thought is a change, every new observance a piece added to the puzzle. Inward or outward, things need to happen in order for a story to happen. Without that you have a picture. But words represent thousands of pictures. All books are film in that regard.
So what does this mean for developing a plot? It means it's unavoidable. It doesn't have to be plotted out in advance or what you build your story around, but it will be there. As a writer, the important thing is to understand what your plot is and how it unfolds into the story you want to tell. If you get stuck, just let something change and see where it leads.