Re: Depressing
The simple fact is, when working on projects you have to make decisions based on resources that are available _today_.
If everyone waited for the next thing to be available before doing something, nothing would ever get done, and thus there would be no next thing.
The engines, albeit 50+ years old, are solid. They have good engineering, a reasonable pedigree and just as important, there is an available supply.
Would it be preferable to have a newer engine? In some ways absolutely. In other ways not at all. Doing something different in rocketry often has as many cons as pros.
The simple fact is - rockets blow up. Not all the time, but enough that it isn't surprising. Seeing as the stack wasn't intended to be on course for human certification anyways, it's a bit whatever.*
Hopefully they can get good telemetry and come to an actual conclusion on loss-cause. The only thing worse than loosing a launch is learning nothing from the process.
Karl P
*It's always sad to see so much work go up in flames, but one accepts it as an eventuality in that line of work.