Kante is 100% a defensive midfielder. Yes, he plays with another defensive midfielder in Matic, but that does not mean he isn't one. Just look at his average position during games.
Your view of football is far too simplistic. Herrera is a very intelligent player... there are times when as a defensive midfielder you sit, and others where you can press and have the opportunity to harass and win the ball. It's not simply a case of "this is your job, you just sit and hold position in front of the back four". You do both at different times during the game... just like Matic and Kante both do at Chelsea.
A Romeu, Herrera, Pogba midfield three is too defensive in my opinion... especially for a club that prides itself on adventurous attacking football.
Anyway, I am going to have to leave this debate soon as I've said my opinion and just can't be bothered with the endless alerts my 'controversial opinion' is throwing my way...