I think the mesh head isn't stiff enough to translate where you hit when the trigger is near the rim (ddrum, 2box pads). The Roland pads work with a piezo trigger in the centre and cooperate with the rim trigger. 2Box always promised that positional sensing would be possible with the forthcoming rubber heads.
But perhaps Deve can explain how it works ...
Rob, as you remember, the older ddrum pads (up to the ddrum3 and the ddrum4 Cast Precision pads) used a center mounted piezo sensor. The positional sensing was able to be determined by the module analyzing not just the signal itself (initial impact to determine the strike velocity), but also the signal reflections as they bounced back from the edges within the pad - just like analyzing the ripples in a pond to determine where the stone was tossed in. As you can see, it's not something that can be done with any accuracy without a fair bit of fast processing power and some very complicated calculations. Move the sensor from the center out to the rim, and the calculations become significantly more complicated and require much more processing power...
I'm going to assume that if 2Box states that positional sensing will be available with the use of their rubber heads, then they would be going with a center mounted sensor in them. It's one of the features I'm VERY hopeful will work at least as well as the ddrum stuff did, as I do like having that feature available to me.
As for why someone would want this feature, the snare drum reference earlier was perfect. On my acoustic snare drums, I change where on the head I hit depending on the textures and effects I want to add to the part. Playing ghost notes out towards the edge and regular notes in the center creates a different texture to the playing than if they were both played in the center or both out on the edge (same thing with train beats, shuffles, etc). Positional Sensing would allow us to do this and still keep the sounds programmed to the center of the pad to sound like you're playing the center of the drum, even at different volumes (fatter, dryer sound) and not have to change our playing style when we move back and forth between our acoustic and electronic setups.