Why is it that many Android apps do not feature a true close application feature? I was wondering why it seems many applications in the Android eco-system come without a true "close" feature?  It seems "different(to be politically correct)" to have to manage if an application is running through the OS rather than the actual application itself.
This is a policy encouraged by Google.  I can't find the exact link, but you can see related guidelines here: http://developer.android.com/guide/practices/ui_guidelines/menu_design.html

The idea is that users shouldn't have to explicitly manage their apps, they can just let the Android OS hibernate or terminate applications on an as-needed basis.  The problem, of course, is that this doesn't work perfectly.  I find it's often too aggressive with apps I want running, and not aggressive enough with services I'm not interested in.  But the goal is to minimize the time users need to spend managing application states.