I mean.. I think Ark needs them. The game is in a healthy state still, nowhere near dying (just putting that out there, so no one thinks I'm saying the game is dying).
Why I think Ark needs them? It gives you some challenge in the game. Caves are okay, and bosses are okay, but if they can give us engaging activities, like the OSDs in extinction, I think it will only benefit the game. Engaging and difficult content keeps players playing. It also gives variety! I imagine they will be optional, though. So long as everything is implemented at least DECENTLY WELL, I am excited. The thought of Dino Races, escort missions, etc excited me. Now, if they do daily/weekly missions, like WoW, that makes it mandatory for you to do them to progress, I will have a problem with most likely. We will see, though. It could be really great or really bad. I am sure we will see in a sneak peek in the trailer, and of course, it releases tomorrow. With Atlas' release, I think they are trying to KIND OF take Ark in that direction, I think they should, because you have this great foundation with which you can build upon. I've always said "events that bring a server together, or make a server go bloodthirsty" are great. I am excited, will see how it goes.