I would love to see this function by default in 2.0. Currently we are relying on some 3rd party plugins for advertisement on forums, I would like you to consider this. You can also add an option into admincp to turn this function on or off. Just a thought.
I doubt we'll ever add this functionality to the core because we've always been about providing a minimalistic software without the "bloat". Many people don't need ads on their forum, and (in my personal opinion) there's also a good population that shouldn't be running ads on their boards (immaturity or greed combined with a tiny forum = ads with no site content).
My personal view is that if you're big enough to be putting ads on your board, you probably know some way to do it, whether it be by editing templates real quickly yourself, using a plugin, or paying someone else a couple bucks to design in the ad spaces for you.
Personally, I'm glad MyBB doesn't put ad space into templates by default. Ads have always been tacky, annoying and just pure ugly when forced into view because some greedy webmaster can't stand people not clicking on the ads. Personally, I'm glad the feature has remained as a plugin and not a built in feature.
(Yes, I despise advertisements.)
better left for template edits by the user and/or a plugin.
Different ad systems have different mechanisms. Ads are best left as plugins.