They added stuff for rakghoul event didnt they?
Yes, they did. Each day opened up new missions and new adaptive gear (the Containment suit) as rewards, along with the quest to get the crimson rakling, etc. I'm pretty sure we've only seen the tip of the proverbial iceberg for the Chevin event. Heck, it's not even 2 days old yet!
They didn't hype this thing for months. The put out a video like two days ago.
BW has been hinting at the next "world event" since the Rakghoul event ended months ago. There's been a lot of hints and hype made at the various Cons and through fan sites and social media by the Community Team. And all the quests for this event were data-mined back when 1.3 came out. I can see how this may escape the notice of some casual players, which is why they released the video to signal the event was about to begin. But the fact that a new world event was coming is hardly news.