Poor implementation of a decentralized exchange is different to whether the idea of a decentralized is better or worse than a centralized exchange - I'd say its better.
Not quite the same, but something like DAI/MKR where everything is done through smart contracts to create a CDP, is better than having a central entity do the equivalent work imo.
The alternative is that we keep trusting exchanges like Binance, wait 6-12 months and post the same thing again about how much money was lost this time round.
While I agree with you in part.
All hacks are because a security flaw wasn't considered or patched. Whether centralized or decentralized.
With a DEX - who will do the coding. Coding by consensus ? There are a limited number of people that understand or comprehend the code. Even the best make mistakes.
Coin networks cannot even get the security right yet. A massive number of coins have been exploited this year and a lot of them haven't even announced it publicly.
It will be a long time before a DEX will provide real benefits over a centralized exchange.(Don't get me wrong - I am pro DEX - but real DEX don't exist yet.)