UKC

Was wondering the actual purpose of the rubber insets in the clip end of DMM draws? A) to keep the krab from moving at all ...which I hate and for me reduces the articulation benefit you want from draws or B) some kind of protection/sacrificial qear surface (which IMHO isn't needed esp if it reduces the freedom of movement). TBH I think I'm just whinging about something I don't like. 

It's called a 'stopper'. It's to stop the carabiner cross-loading. Pretty much everyone puts them in quickdraws, not just DMM.

As you know, the krabs are only around 1/3 as strong if they turn sideways. When you use a quickdraw without a rubber stopper, shaking the rope about as you climb twists and turns the rope-end biner out of place. Pretty much all draws except Edelrid 19G's have stoppers. Nobody puts them on the gear end, because it would act as a lever and make it easier for a nut to pop out when the rope feeds up through the runner.

Petzl sell their stoppers individually, and I've put them on my 60cm extenders to stop the (DMM Revolver) rope-end biners from being cross-loaded, which I've always found a scary sight when climbing above the gear. I want the sling to move freely, for the reasons you've described, but I really don't want the krab moving about on the sling. Guess it's a matter of personal preference, but personally I'm not sure I'd take them off my draws even if they were removable.

As above plus it makes them easier to clip.

If you climbed sport you would appreciate it.  I suspect that you don't.

Al

I have a few old draws where the rubber has broken and they are notably worse. I tend to fix them back in with climbing tape

Why not buy QDs without them if you don't like them, there's plenty about.