The inclusion of MediaWiki:<meta> pages in the base Article, templates, etc. dumps, such as the English Wikipedia, cause major problems if you are trying to import these dumps into a Wikipedia enabled for another language. Many of the navigation menu's get trashed and corrupted when these MediaWiki labels for the English Wikipedia are included in the base article and template dumps. It certainly is ok to include them in the dumps which supposedly contains "everything" (the .7z dumps) but they shoud be stripped out of the base dumps which are supposed to just contain the articles and templates for the articles.
If you import one of these dumps without stipping out the MediaWiki: specific articles which add menu items, etc. the navigation bar gets messed up and things likfe "Recent Changes" no longer map properly in MedaiWiki.
I think its OK to leave some of the MediaWiki tags, like site notice and "contribute to Wikipedia" kind of stuff for GFDL and attribution, but the inclusion of menu pointers which affect menus should be stripped out as they will cause major problems on MediaWiki's enabled for another language.
Jeff