Jeb...something about a previous life you want to tell us?
munk - the handle is intentionally fat near the bolster. If you adjust your grip to be "back-strong" then you won't slide. Let me explain.
When I use a "fighter style" knife, it is "pinched" using my first three fingers (thumb, pointer, middle) The other fingers are loosely gripping it.
When I use a khukuri for chopping, I am gripping mostly with my thumb and middle finger....followed by my pointer. Fourth finger bracing.....pinky loose. Allows for a snappy action.
When I use the seax....I am gripping mostly with my fourth finger, then pinky, then middle finger. Pointer is for bracing.
make sense?
With my grip adjusted like this, most of my grip energy is in the skinny part of the handle, keeping my hand from slipping. I've tested this (with the blade taped for safety reasons) and have managed to stick it tip-first into a 2x4 with no problems (after a few adjustment thrusts).
Every new knife style requires the user to adapt....learn to use the knife the way it was intended/designed.
You could make the same "why no guard" argument against a puukko....yet that is a knife that has stood (and continues to stand) the test of time.
There are those who say that sloppy knife fighting is what made us dependant on using a guard.
I do believe that having a guard can lead one to become overconfident and sloppy. But a well-trained hand is a well-trained hand....regardless of features/enhancements.