I have no idea why 99% of the people who run debug mode have it enabled.
It simply is not required unless you are developing.
I think we need that setting to be broken down
For example, we have more than 1 administrator at my forum, and it is really useful that everybody can see how long the page took to generate and how many queries it is attempting. Sadly, sometimes there are addons that add 80+ queries to every single page and take the CPU usage up by 100%, so having eyes on those numbers IS useful.
However, debug mode also enables people to edit the master style, master language, admin templates, etc, which is absolutely not the point. And I would either need to communicate "even though you see this, do not edit it", or enable and disable debug as needed (like, just after installing one add-on).
Plus, if I remember correctly "debug mode" triggers some special setting like the explain plan for queries. (it sets the profiler on, on the Zend page). Which is horrible, because then it becomes misleading. I hope this makes sense:
Page without profiling loads in n seconds
Page with profiling, loads in n+m seconds
With debug mode, you see the load time (n+m), there is no way of seeing the load time WITHOUT the profiling
. The load time is permanently misleading.
I have even considered hacking into whatever drives the display for processing time and queries, to make that show all the time, since that is the only bit I need of debug mode in production.