I have B&W Clear filter on all my lenses, no exception for shorty 
Sorry, I have to ask. Why? The cost of a decent filter is about half that of the lens. And the front end doesn't seem too vulnerable. I know the hood is ridiculous for the shorty but does it need protection?
I have a B+W filter on every single lens ... why? I shoot a lot in the desert and where I live dust is flying around everywhere ... all lenses need protection, the question is not about money but about not being able to make an image because of broken and/or scratched up lens front element ... BTW a decent filter does NOT "cost half that of the lens" ... one of the best filters out there is B+W XS Pro costs only $33 ... B+W UV filter costs only $20 ... Tiffin UV Protector filter costs only $5. So I am not sure what decent filter you are talking about that costs half of the lens.
Ok fair enough, you use a filter to keep out the dirt. But my point is why does a person who is not running around the desert and is just out doing basic street photography need a filter on their shorty?
As I said earlier, "all lenses need protection" ... even if you are "not running around the desert" ... OK lets imagine the following scenarios:
You are carrying only 1 lens (or the only lens that covers 40mm) and you have a small accident, could be dirt, oil, grease whatever on the lens ... OR you come out of a nice warm car into a cold outdoor environment or vice versa (this happened to me on quite a few occasions), you see a fantastic photo opportunity, but your darned lens is foggy due to the temperature change, which one of the following would you feel is safer, faster and/or comfortable to do:
a. Search, pull out and clean the lens with micro fiber cloth that is good enough not to scratch the front element?
b. wipe the filter with your shirt or even a tissue?
All lenses do not need protection.
If you say so ... its your equipment, your rules.
Does my P&S need a filter too?
That's a question you have to ask yourself. But none of my P&S can take filters ... if they could, I would.
My point is where do you draw the line between protecting an investment and overprotecting something that is almost disposable?
If the lens can take a filter, I'll have one on it, that's where I draw the line.
None of my lenses and/or cameras are disposable or "almost" disposable ... they are all valuable tools which I want to protect so I am not caught offgaurd by not being able to make a picture. It's not about money, its about not being able to make a picture at a given situation.
Surely a small rubber hood would do that?
Not for me.
Why pay $33 for a UV filter for my 50mm lens that cost about $80?
I've already answered this question earlier.
BTW, I had a $19 B+W filter on my 50 f/1.8 lens that cost me $99
By your theory it must be protected right?
As far as my lenses are concerned, that's a resounding YES! ... but that's just me ... as I said, your equipment your rules, my equipment my rules.