Did the folks creating the containers in the article believe themselves to be creating unsafe storage? I doubt it. Our current situation is no different. We think it's safe because we haven't seen it break, when we do see it break it will be in an unexpected way, probably ahead of the time we thought it'd break.
80 years later, we know a lot more, and have a different set of expectations for how to store and handle nuclear waste.
It's fair to be skeptical, but not fair to condemn them based on past mistakes which have been specifically addressed. It would be like saying modern cars must be unsafe, because cars from the 1940s don't have seatbelts or airbags. It doesn't follow.
You could also say "well, we know about some safety issues, but what about the ones we don't know about yet?" but that attitude extends to all of science and engineering as well. We have to proceed with caution, but proceed nonetheless.
It's absolutely insane to me that people on this site can be so distrustful of government when it comes to things like privacy/encryption/etc, and so trustful for things like continuing to provide funding for maintenance of nuclear facilities, especially given current governments have proven themselves undeserving of trust in either regard.