I'm pretty sure the counter is still being updated as before. It's just not shown by default anymore. Now you have to click on the review title to get to a single page with only this one review on it, e.g. http://www.amazon.co...views/R3S23J70VFH350

As you can see,
19 of 20 people found the following review helpful

I'd missed that -- it's still pretty well hidden though (which was my complaint). I suspect it may simply be the case that they either haven't changed that aspect yet, or dont consider it worth the effort of changing it.

Re being logged in:
that was simply a case of me noticing that they were still showing the negative votes there on my own reviews (when logged in).