Meshes added depend on the viewport and are not placed on their default place It's quite hard for me to describe the issue in words.

I'm gonna drop these pics to explain the issue.

Say I have my 3d-view this way:



When I add a mesh, it's created and placed in the 3d-view this way:



I want it placed upon creation this way, however my 3d-view is directed to:
Open the tools panel (Press the T key) to have access to the creation parameters (or press F6 after adding your mesh). Make sure that the Align to view box is disabled.



If the question is about why is the mesh not created at the center of the grid, then the answer is that objects are created where the 3D cursor is on the scene.



To reset the 3D cursor to the center of the grid press Shift+C