I'm really confused about type, and so is everyone else (

).
Now that Construct doesn't mean immune to sneak attack, do we even
need each monster to have a "type" in this sense, rather than some keywords?
I don't think the distinction between Humanoid and, say, Fiend is very valuable. There can be Beast Fiends and Monstrosity Fiends and Humanoid Fiends, after all.
What I'd prefer to see is... well, exactly that.
Give something a Natural keyword if you want the druid to be able to compel it.
Give something the Immortal keyword if you want it to not need to eat, sleep, or suffer disease.
Give it the Undead keyword if it's animated by the foul forces of unlife.
Give something the Humanoid keyword if you want it to be able to be Charm Person'd.
Give it the Fiend keyword if you want it to be hedged out by things that affect fiends. Maybe all Fiends are immortal? They don't have to be, though!
A Natural Immortal Undead Humanoid Fiend? Seems weird, but I've seen worse!
I remember suggesting exactly this on these boards on the leadup to 4e. Someone with way higher postcount than myself (I want to say Ari Marmell? But my memory is shot

) had already seen what was coming thanks to prerelease NDA. Whoever it was defended the oncoming design.
I wasn't convinced it was a good rewrite of the 3e system then, and I'm still not convinced we need that core of "monster type" instead of "monster keyword".