If you are referring to a “dolphin attack”, it has also been tested and has run Siri on several devices. The articles I read about it didn’t test a HomePod, but that doesn’t mean it doesn’t run on one. If this is what you are referring to, it has to be run within 5 feet of the device which makes it much more dangerous for phones since most Echos and HomePods are inside people’s homes. Also, controlling an Echo or HomePod really doesn’t do much for anyone.
As you say, bigger doesn’t necessarily mean better, but we won’t know if Apple just cut costs here until we get some breakdown comparisons. I would argue that pulling out SD card slots, HDMI, etc from Macs or Headphone ports from iPhone and ipads, removing chargers from cases, etc… did not necessarily make things more efficient for the user. At least with the Mac, they figured that out and put ports back in on their MBP. On the 2016 MBP they put in the touch bar, but removed the physical ESC key… not more efficient for the user. We could also talk butterfly keyboards which were worse than their predecessor.
Yes, removing weight and size makes this cheaper to ship, which is more efficient on their end, but is it better for the consumer? We won’t know until we get some hands on tests and some “ifixit“ style breakdowns.
In any event, if you want the best sounding Homepod that Apple has on the market, this is the only game in town. It has sensors and other capabilities not in the original, so that is a bonus, as well.