We deliberately avoided implementing such functionality.
Stripping white space is not as important in modern days, as search engine algorithms have improved. These days, search engines penalise you for slow page loading times more so than content-to-code ratio, and we don't want to include any functionality that would cause more harm than good.
Removing "last poster" can be done via your style, which would be "free" (in terms of resources". Again, pointing to the page loading times - we want to minimise the amount of rewriting of page content in order to keep the impact on page load times to the absolute minimum.