Sure the F1 is big but not so much regarding the needs of today.
On the photo gear side - you're right - the need to keep at least the most useful couple camera/lens is evident. Even the D profesionnals Nikon models - 'tropicalized' and so much - catch dust if you dismount lens all the time (even in a clean area).
But that's not all the avantages of the F1.
If you are overseas in hard assignments (especially embedments with army in desert area) you can spent a couple of days outside, without you main travel bag (for exemple during stops with military planes or couple of days mission outside your camp). With the F1, you can put the necceseray 'living' gear (spare shirt, razor, etc.) along a book, sun glass or small lap top.
And 'in action' with digital, you don't need anymore to have a full bag aside, so the F1 can stay behind you for a while, in vehicle or tent.
I try my new one (a black canvas) in Afghanistan last year and can add that it is also very good in heavy dust conditions (and Afgha is the testbed for that !).
I spent a whole day patroling on 'Highway one' in very heavy dust (my F1 was inside an armored vehicle with open hatches) and no dust at all inside bag.
Definitively the best for me !