That is a valid point, but it could be even easier to detect when no code/p tags were used, and refuse to create the node :) or force an extra preview :)
I thought about that during my reply, but realized that it was an example of a node that didn't need any <P> at all since it was a single paragraph. Heuristics will always get things wrong and annoy people. Maybe enforce it for newcomers or anonymous posts only, then back off.
As is, it does serve as an indicate as to the competency of the poster and how much attention to detail he invests.