You are exactly correct that ZigBee doesn't have a brand. That is a big difference between Z-Wave and ZigBee. Z-Wave is a product sold by Sigma Designs and its licensees. ZigBee is an IEEE open standard that any company can use for generally free. (The ZigBee Alliance makes money by certifying products.)
There is aso little argument that money drives the world, and the way we perceive the world. You can have great technology, but if companies aren't going to make money from it, its likely you'll never hear about it.
My wife has lots of allergies, and for her these allergies can lead to mucus in her chest which can lead to Bronchitis which can lead to Pneumonia which can lead to hospital visits. It can be a very serious thing and she typically can have problems several times per year. When I first met he she would typically be sick with this condition for 5 to 10 weeks a year, and miss work for 2 to 3+ weeks of that.
For years we went to specialists after specialists to try to find what would help with this, and she also went to an allergist several times per year. Needless to say we always returned from the doctors with a list a long list of drugs, steroids, antibiotics, neutralizers, etc. These were not only very expensive (even with insurance) but they were pretty serious with unknown long-term risks. Even worse, they didn't even work very well. Every doctor's visit would yield a new handful of the latest drugs to try.
Then about two years ago I was searching on the Internet and I find this device for $50 that you blow into that causes a rhythm that causes the mucus to dislodge. This along with some over-the-counter medicine have reduced her episodes which lasted a month+ (usually requiring antibiotics) down to the point where they last 10 - 15 hours or less. She missed no work last year due to this illness. Not a single day.
So why didn't any specialist recommend we try this $50 medical device instead of the literally 100+ medicines we must have used over the years? Simple. These medicines are what the drug companies want you to buy. They get money which pays for the drug reps. which drops of drug samples to doctors which continues the cycle. Doctors aren't evil, its just what is pounded in their heads day after day.
Technology is no different. There are so many instances where it was the money which determined which technology choice won, not the technology itself. There is no doubt that this has been the case for Z-Wave and ZigBee, and probably will be for some time to come. But I think here its a bit different. Where there is definitely currently more Z-Wave around than ZigBee, I think that the overwhelming use of ZigBee in non-home automation application will pull it into that as well. Long-term, its hard to beat open standards.
As for the metal gang boxes, that doesn't make things as bad as you would think. With ZigBee it wouldn't be a problem.
Interestingly ZigBee has a different problem that few people realize, and I got zinged by this. ZigBee is a mesh networking standard, BUT battery operated devices DO NOT forward the packets of other devices. Only line powered devices do this. In other words, ZigBee will likely work terribly if you ONLY have battery operated ZigBee locks. I had this problem at the start. But add in some line-powered devices, like thermostats, light switches, and range problems will be a distant memory. I'm not sure if Z-wave works the same way, but with ZigBee, having a few line-powered devices is just about mandatory. Once you do that, it really works great. I think I change the batteries in my ZigBee locks maybe once per year, if that.