This REST call was meant to aggregate stats for several buckets. And it used to do so long time ago (Northscale Server 1.0.3). But after 'membase' bucket type was introduced, it worked only for a single bucket and failed with badmatch error otherwise. So now it just causes confusion because some expect it to work and it obviously doesn't. The proper way to grab bucket stats now is /pools/default/buckets/<bucket name>/stats call. So it makes sense to discontinue the old REST call.