Vim: Smart indent when entering insert mode on blank line?

cc will replace the contents of the current line and enter insert mode at the correct indentation - so on a blank line will do exactly what you're after.

I believe that the behaviour of i you describe is correct because there are many use cases where you want to insert at that specific location on a blank line, rather than jumping to wherever vim guesses you want to insert.

Well this actually wasn't as bad as I thought it would be. One way to enable this is to add the following to your ~/.vimrc

"smart indent when entering insert mode with i on empty lines
function! IndentWithI()
    if len(getline('.')) == 0
        return "\"_ccO"
    else
        return "i"
    endif
endfunction
nnoremap <expr> i IndentWithI()

It simply checks for an empty line when you hit 'i' from insert mode. If you are indeed on an empty line it will delete it and open a new one, effectively leveraging the working 'open line' behavior.

Note: "_ before the cc makes sure that your register doesn't get wiped