>Plenty of cars have a "traffic jam pilot" feature that seems indistinguishable from this. I don't get the hype behind this announcement.

The difference is that the company is putting their money behind their promises. It is like you want to buy a product , one company gives you 5 years warranty and the other offers 0 days warranty but they show you some ads and cherry-picked stats.

It's going the step from being a "driver assist" feature where the driver is liable for things to an autonomous hands off feature with MB being liable if it crashes while you're using it.