Ps4 has taken the same path that Facebook did with their smartphone apps, keeping chat and all other things separate. Sony just released the new app called PlayStation Messages which allows you to chat with your PlayStation friends when away from the console.
Chatting with your PlayStation buddies before required you to do it via your console directly or the PlayStation App which was not made for the sole reasons of chatting with friends. So Sony is fixing that by having made a separate app for your chatting. The feel of the app is of a normal chatting app really it has support for stickers, people who are online and what device are they using to talk to you.