"Why not create a ‘templates’ directoy and a ‘base.html’ either in project’s directory or in the apps’s directory, because creating the same templates directory and same base.html for every project is not DRY?"
There's nothing wrong with that. Even the djangoproject.com website does it: http://code.djangoproject.com/browser/djangoproject.com/djan...
"Why serving static files in development has to be a additional setup, as no developer wants to setup a server for serving static files, I am aware of ‘django.static.serve’ but still that is an additional setup, why not create a sample media directory and a url for the same in urls.py ?"