On my Nexus 4, I'm visiting the Stack Exchange sites in full site modus and quite often in landscape. This gives me the same freedom I have when visiting the sites on my desktop computer.
On all SE sites, buttons or tabs are used, to select between the different items; see lower red circled area. These items are easily selectable with a finger, because of the relative large surface the buttons and tabs occupy.
The items in the first red circled area however are difficult to select with one's finger. They're pretty close to the navigation bar and seem to be just hyperlinks.
In order to improve the usability of the site, on different media, I would suggest to increase the selectable area of these items, so that they will bring distance in respect to the navigation bar and increase the surface area.