There are two main modes of story-telling: the story-teller and the writer. The story-teller mode mimics oral tradition and predates the writer mode. There is much to be learned from each of these writing modes regardless of the type of writing you do.
There are several story-teller modes (Navajo oral tradition is quite different from, say, the Iliad). Modern story-teller writers include recorders of folk lore and comedic writers. Modern story-tellers have several traits in common. Modern story-telling writings are great resources for people who want to study flash fiction, short story, or longer narrative forms. This is partly because the story-teller writing style tends to be conversational, more concise, and have little description. Story-teller writing also tends to be very brief and yet holds true to story structure.
The writer mode also comes in many flavors. What I mean here is a writer who is trying to be “writerly”. For instance, lots of description, bigger words, and formal or artificial language. I tend to be write formally because that is my natural voice. This is fine for blogs but I work to tone it down for my books.
As a rule of thumb, short works (such as flash fiction and short stories) are typically done in the story-teller mode. This is because there is no room for the descriptions that are expected in longer works. (There are exceptions and I’d love to hear some of yours.)
In novels, there is more room for the writer mode. There, narrative voice runs the gauntlet from story-teller (like Terry Pratchett) with a very informal style to writer (like Terry Goodkind) with a richly descriptive and philosophical style.
I wouldn’t say that one length of story is superior to the other, just that different traditions and conventions are in place. And isn’t it fun to break those in works of any length?