since the game is cartoon style, i think it's just about right that the enemies has a highlighted area around them (Red, Purple and Yellow)
#red light
pure path
vagrant mural
First person to complain about easily distinguishing his enemies... Neat. xD
Kidding aside, this feature helps the players to easily distinguish if there's an enemy or if it is an enemy or an obj, etc. This kind of feature isn't really new in any fps games, even valoPC has this feature that you can change the color highlight of your enemy for you to easily see it.
It's not really just for the art style of the game, it's mostly for those peeps who have bad eyesight and can't see the difference between an obj or player.