Because aren't those two titles higher in authority than 'Lord'? Don't their commands overrule the commands of a 'Lord.'
He said He has "overcome the world." Doesn't that make Him its conqueror? Wouldn't the world then call him 'king' or 'emperor' or 'czar'?
Looking through the Old Testament, I see that 'they' (assuming the translators are right) always called God 'Lord.' Why didn't they call him 'King'?