The lower sample at the left is a common menu item. There is no doubt that any visitor can read the menu items, even with the low contrast color scheme. However, even two menu items take up a lot of space and command too much attention. Plus, the two items here weigh in at over 5 times the file size of all the menus shown above. The best menu system will fade to the background when it is not needed.
Menus created with large type and bold colors often overwhelm the content.
Test this when you see a site with large, bold, navigation. My bet is that you will spend more time clicking from page to page than actually absorbing the content. However, teaser menus are designed to direct our visitor to the places we would like them to go, or where they will fulfill the purpose of the visit. Site navigation should be integrated well into the page design, but subtle. If you find that your design calls for plain text, consider using plain text.