Another issue I have with it is that it has been my experience that the majority of the problem is that people don't understand what code tags are or how/why to use them. An additional notification stating to use code tags is a moot point, and an alert prohibiting the posting process is just going to be more frustrating than anything else, really.
Correct me if I'm wrong, but I'm pretty sure that Davey has the same experience as I do, with the constant PMs asking, "What are code tags and why do I need them?"
I think that if we did implement this solution, there would be an increase in the percentage of people posting with code tags. But there would also be an even more significant decrease in the percentage of new posts. Essentially, all the people who post without code tags would instead get frustrated and/or confused and simply not post at all.
I am hesitant to follow in the footsteps of sites such as CProgramming, as that site has been around MUCH longer than DaniWeb, and hasn't seen anywhere at all close to the growth or traffic that we have. Perhaps this is one of the reasons why.