I suspect PADI staff realized that, if the 'minimum' depth for the Deep Dive (aka Dive One in the Deep Diver specialty) was only 60 feet, the likelihood of meaningful narcosis developing was limited. So, for the past decade or more, the primary task has been color recognition. And, colors do change sufficiently at 60 feet to make the task meaningful.
I suspect you realize there were invisible [sarcasm] tags around that, precisely for that reason. I also suspect colour recognition is indeed a more useful exercise, although I can think of a couple of dives that didn't look as blue at 30 metres as a reef wall usually does at 20. And I've no idea what 60 feet in fresh water looks like: midnight green?