Mr. Harsey,
Since I'm a blade enthusiast (freak), I always carried way too many sharp and pointy things in the field. In my early days I was stupid enough to lug around a crew-served machete but have since scaled down a bit. My knees and broken back started talking to me so I had to be a bit more practical. However, I still carried my SF in Iraq last year.
My impression of Big Army's opinion on knives and other bladed weapons is that they are too war-like and therefore politically incorrect. Plus, there's the risk-adverse mentality that someone might cut themselves. Not to mention they don't go well when everyone is supposed to be dress-right-dress.
I will admit that carrying knives was much easier before the army decided to dump an extra 50+ pounds of sh*t on us in the form of body armor and all the other new gadgets we are given to attach to our once lightweight carbines.
The lack of room on one's equipment and the sake of one's own health may also be playing into the lack of big fixed blades in the field.