You are right, 400 million dollars although it is a huge number, it did not seem so big compared to the whole market cap of crypto. It is indeed a very bad thing with negative effects over how cryptocurrencies are perceived by the people new to them. Instead of looking secure as they are, they will look like they are easy hacked and the current centralized economy is much better.
I really hope that this kind of things will not happen again and that decentralized exchanges will soon evolve so much and replace the current centralized exchanges.