The title says it all, just a huge convenience not having to open up the "My Drive" folder everytime I open Google Drive?
There is no way of default-opening the folders on the left bar in native Google Drive, but what might be helpful to you is that Google Drive will default to whatever main-frame view you had open the last time you logged off.
What you could do is go to "My Drive" and make sure the items in the main view are sorted by
title This will put all of your folders at the top of the list because it also first sorts by type.
Now every time you log in you'll see this view, unless you change the sorting afterward.