Why are we even using black and white tags?
Lighting. The Sun, incandescent, and halogen lights have pretty good color reproduction. But LED lights and fluorescent lights do not. LED lights and fluorescent lights are designed to look acceptable to human eyes. And they can be reasonably good at it. But cameras are not human eyes; color gets all fucky when you look at it through a camera.
Cameras. The tag you linked to uses the LAB color space; one channel is brightness, one channel is blue vs yellow, one channel is red vs green. Cameras almost always have BGGR arrays; on a 4 megapixel camera, you will have 1 million blue pixels, 2 million green pixels, and 1 million red pixels. So if you use a normal camera to read a tag in the LAB space, you have 4 million pixels reading the brightness channel, 3 million pixels reading the red-green channel, and 1 million pixels reading the blue-yellow channel.
This is essentially false. Plenty of industrial cameras are black and white because of their speed and light collecting advantages. This matters for high speed identification. Going to color would not be an upgrade.
"missed opportunity"
Limited information density just isn't nearly as big an issue as you seem to believe.
Colors work great until they don't, for non emissive sources they depend on ambient lighting. A black and white code can be read with under virtually any color lighting (it doesn't even have to be in the visible spectrum). And if you've seen anyone futzing getting a read of an eticket off an emissive device such as a screen, that is just much worse once color is brought in.
Most auto ID applications have limited keys and identifiers encoded in the symbol. Just as color cameras are ubiquitous, the same goes for network connectivity, you don't need to store massive amounts of data in the symbol. If color symbols were really that much of a win they would have been adopted in industry. Attempts by groups that don't understand the subject have been made over the years, this is not new:
https://en.wikipedia.org/wiki/High_Capacity_Color_Barcode
"Yes, it requires different printers"
This is quite an understatement. There's no cheap upgrade path from monochrome thermal printing technology (or laser engraving), that's why they have never been replaced all these years.
Color imagers were readily available long before 2005. Color printing has not changed much at all in the past 20 years. If color symbols made sense they would have been adopted a long time ago. They are almost always the wrong approach, too many problems for too little payoff, that's why they are uncommon.