Lots of reasons to look at viruses that already exist on the planet. The article clearly states that this is an existing variant of a virus normally found in pangolins, nowhere in the article does it suggest this is a human modified variant of the existing virus. This study only shows that the virus has a really effective kill ratio on mice who are genetically engineered to serve as a proxy to using actual humans to study the possible effects of this virus on people.
Now, I am not sure how much interaction humans and pangolins actually have on the planet, I hear they're a delicacy I haven't tried though. Would it be any better if this study was on the many forms of bird or swine flu that we haven't yet found in the human population?
I am guessing there are an awful lot of viruses out there that can kill people that we simply don't know much about. Some in odd species that people don't routinely interact with, and very likely some frozen in glaciers and permafrost that ran their natural course through the population thousands to hundreds of thousands of years ago and then got relegated to history, temporarily.