What’s wrong with it, exactly? It seems pretty standard and conventional to me.
It reduces things to a sole cause – ceteris paribus – but that’s a valid way of examining hypotheticals.
From another thread, if Archduke Franz Ferdinand were not assassinated, WWI would still probably have happened, so “Just because the Archduke wasn’t assassinated doesn’t man WWI doesn’t happen.”
I do see the temptation to put a comma in the middle, but I think it should be resisted.
My main problem with it is that a “just because” isn’t much of a subject for a verb. The paper linked to by RadicalPi addresses this in section 4.1, and suggests that the subject may be unexpressed in this case.
The paper also shows many other similar expressions based on “just because”, implying that it’s pretty standard and not something the 5th-grade teacher would frown upon. Guess I’ll have to get used to it.
All three are incomplete. What we would say here is “Just because the sun is shining doesn’t mean it won’t rain 10 minutes from now, or even right NOW.”
I think you’re missing the context. The principle is usually stated because somebody has tried to argue that opposite; they implied that it won’t rain this afternoon because the sun is shining now (or, metaphorically, that a bad situation won’t exist in the future because it doesn’t exist now). So you’re refuting the specific logic that somebody is using in an argument.
I disagree that that subject is unstated. The subject is “Just because the sun is shining.” It’s a noun clause. There is also one at the end of the sentence “(that) it won’t rain tomorrow,” where “(that)” is implied. The sentence is merely SVO–subject verb object.
“That the sun is shining” is also a noun clause. “The fact that the sun is shinining” is an article, a noun, and then an adjective clause. But they all still have a noun clause at the end, so I don’t get the issue.
The only issue I ever have with noun clauses is that they sometimes get so long they become hard to follow. When that happens, I use the following construction: “Whether the cat is really the dog and the dog is really a cat and the horse is just a horse–that is the topic I am discussing.”
Though, in writing, I tend to just rework the sentence. “The topic I am discussing is whether the cat is really the dog and vice versa. And possibly whether the horse is really a horse.” Unless, that is, I’m just trying to write like I speak, or I don’t take time to edit.