Recently I had to add a lot of attributes to a lot of elements. Needless to say, current system is functional but extremely time consuming even if need to add a few attributes. It would be much better if there was some sort of a custom field where you could paste multiple attributes at once. So instead of having to add new row and jump between name and value and being able to paste only one at a time AND having to apply them, you could just paste "data-this="foo" data-that="0" data-whatever="boom" and be done with it.
The whole attributes interface is not ideal IMO, I constantly have to resize the window to see what I need at a glance, but that of course makes the HTML window very small :/