Have I "travelled in words"?

Last week I received the first serious critique about my way of writing. How do I feel about that? I feel good, but not totally comfortable.
When you put your ideas on a sheet of paper they usually make a lot of sense to you. But, unfortunately, sometimes they don't seem clear to people who read them. Well, that was what happened to me. I thought I had written a story, but actually I hadn't. It happened because a story is supposed to be structured , but mine had no structure at all.
The point is, why hadn't I realised this while I was writing it? Maybe because it seems to me , even right now, that my "story" was OK. I can see a situation 1, a conflict and a situation 2 on it. But why can't people see it? I think it's because they are not me. All the structure of my text was in my head, but I didn't put it on the paper. So what did I put on the paper? Hmm..I don't know.Maybe only ideas. Maybe I just have "travelled in words"... But even travels are supposed to have a beginning, a middle and an end. Don't they?
Something that is not clear to me is : why do stories must to have a pattern of structure?