I love it when I see any form of Ethical hacking which only brings out the best in any product. I believe it's worth it if the ETH network is subjected to a stress network test for vulnerabilities so that once ETH 2.0 is launched on proof of stake there are not going to be any issues of the system being hacked.
Stress testing and finding bugs are two different things though. I used to be a part of a quality testing team before, that's why I know such things. Stress testing Eth 2.0 means that they need to overload their system in which they are not offering as of now.
What Ethereum calls is for ethical hackers trying to penetrate their system, to find flaw and exploits. And with stress testing, you can just write a code to to give the system too much that it either it can handle it or not.