Thanks for the explanation. That makes sense. In many contexts that would be advantageous. In regards to charms people have used infinite edge to justify how great the feature is and easy for users to access because of it (and by no means am I suggesting you are one of those people or that you even like the charms implementation). What they overlook is the mouse actions after the target has been hit and how easy it is to slide off the charms bar while moving up or down the bar which causes the bar to disappear. So again in the right context infinite edge makes sense.
Sliding off the charms isn't really a problem if you swoop around the corner in one smooth motion rather than stopping and waiting in the corner for a second. The momentum from moving to the corner will carry through and keep you pinned to the edge during the move up (exception: shared edges on multimonitor, which I still find to be somewhat awkward/unreliable even after the improvements in 8.0RP and 8.1).
I find the gesture to be fairly comfortable, efficient and enjoyable when done this way, but I think the real problem is the visuals and animations don't really guide users to the "right" way of performing the gesture and tend to make people think they need to wait in the corner until the charms hint appears.
BTW, it's interesting to remember this actually wasn't their first design for this mouse affordance. If you recall in the first Win8 Developer Preview the right-hand "hot corners" didn't exist, and the mouse way of using the charms was as a more compact "menu" that appeared in the lower left with the Start button. The main problem with that design I think was the excessive mouse travel it added to using any charm flyout (since they still appeared on the right) as well as being less consistent with the touch approach (not a big deal, but consistency here is a nice-to-have for ease of learning and comfort when going back and forth between input methods).
The CP design solved those problems but also introduced a couple of new problems. The first is the weak visual feedback as discussed above. The second is more subtle, but I think even more significant: by separating the mouse affordance for the charms (right corners) from the efficient and familiar mouse affordance for Start (lower left corner) access to core OS functions became scattered - there was no longer a single entry point for fundamental Windows controls as the charms were intended to be. I think complaints like "why is shutdown/restart in a charm?" would be less prevalent if Start were perceived as "belonging" to the charms and so the charms were perceived as the top-level starting point for finding Windows functions, rather than an add-on.
Personally, I'd consider going back to the DP design but just moving it from the lower-left to the lower-right corner. Of course this would mean moving the Start button to the lower-right as well ... would that freak people out? :)