In reply to Jeff Chandler.

You can also click the + icon to the left of a hovered empty paragraph block to open the block ui and convert it to any block. It's just not in the right side more options menu.

Demo: http://www.giphy.com/gifs/mIQHnBGelLRxvNUwUd

I do think the / command could be easier revealed. If you have a blank paragraph block that isn't actively focused it does have placeholder text of "Add text or type / to add content". But the problem is when hitting enter after a paragraph that doesn't show because the block is focused.