I am saying that I believe that the typical classes don't address the concept of situational awareness very much, and this could be easily handled by (as you suggested) handing an OW student a camera. Or giving her thick gloves. Or a thicker wetsuit and more weight, etc. etc. Easy to do and it should illustrate the point really well to most students.
For a novice/trainee diver, 'handing them' a BCD, reg, mask and fins tends to cause sufficient task loading to significantly decrease situational awareness. Over the duration of OW training, that situational awareness improves as task loading decreases with familiarity.
Beyond OW training, most continued education courses tend to provide the task-loading stimulus you are suggesting. The AOW course, in particular, does a very good job at providing a graduated increase in task loading.
Adding any equipment, environmental or activity-related supplemental demand to the list of the diver's in-water responsibilities will cause an increase in task loading. The diver needs to concentrate on the new demand/s, causing any weaknesses in their existing core skill-set to become apparent. That presents itself as a degradation in their overall dive performance. As they adjust to the new level of task-loading, their performance improves.
If the OW / AOW classes did this,....
I believe they do...
Two people take an OW course. One in 82 degree tropical water in Bonaire and one in 50 degree water Puget Sound. ...identical in every possible way. ..., the Bonaire certified diver flys to Puget Sound and rents all appropriate equipment to go diving. The Puget Sound certified diver flys to Bonaire and rents all appropriate equipment to go diving. Both divers will be diving in the exact conditions and equipment that the other was certified in.
Of these two divers, which one is less likely to have any problems?
It's a bit of a false premise to suggest that all other environmental conditions "are identical". Obviously, that creates a very biased comparison.
All things being equal, except temperature, then you have a simple balance between heavy exposure protection and light exposure protection. Between higher manual dexterity and lower manual dexterity. That is all.
In reality, all things aren't equal. Any given environment or location presents a unique pattern of conditions and demands. Water temperature is just a single one of them.
The 'list' of problems that the Puget Sound diver could encounter in Bonaire could go on for pages...