Title? I don't need no stinkin' title.
For the umpteenth time, it gives me a little more indication of how they think, view the world and are likely to react. As it says in the MM "A monster’s alignment provides a clue to its disposition and how it behaves in a roleplaying or combat situation."How? What does alignment tell you about those monsters that those paragraphs don't?
But that's also dodging a simple question. Take alignment out. The monster's fluff I quoted still makes them evil. How does it change anything other than taking away an additional piece of info that helps people know more about the monster at a glance?