Joomla images folder permission for Media Manager -

I have trouble with Joomla 3.3.6 media manager. My folder permissions for pictures / pictures and below all 755 and my files are 644, because it is recommended. But when I try to upload a file using Backend Media Manager I get:

  Warning: Failed to move file! Unable to upload the error file  

and

 .  

For 777 / My folder and file permissions for pictures definitely fixes the problem, but this is bad behavior, right?

Can anyone help me why not win work with 755 and 644? should be OK?

EDIT: I have not enabled FTP in the global configuration. Is it necessary to use proper permissions?