if you write HTML using all the optional opening and closing tags the standard allows

I personally believe -incidentally- that by inspecting the source of all of my posts, but possibly for the very first ones, you'll find our that I always close all tags: I like to think XHTMLishly. So that wouldn't be a problem for me and I actually find the grey tags very useful, for they can only highlight an error on my part. I suppose that's cssable too, and in that case I may even turn them bright red instead...