Your comments show, that your intention is to have an as proper looking forum as possible. So, if you feel a need to add the pre tags, why not? The only problem seems to be: How do you get informed in time, that there's a post missing the pre tags? You told us once that you do not read every post, sometimes. Should we give a message to you then, if we find a pre tag missing post?

I think most people here would add pre tags by themselves, if they would know how to do it, and that it's needed at all. Not mentioning the always lazy people who try to save time by even omitting characters...
It's in the own interest of everyone to write a post properly if he wants to appear as a professional. Lots about HTML formatting can be learned by just looking at the source code of displayed page. By this I learned some tricks from somes of Michael's posts. (It's never too late to learn from a master!)

How to post code snippets properly should also be focused on and explained in the 'forum rules'. Perhaps with a tiny example.

Kai