This research is part of a larger trend in biology where things once thought to be impractical are rapidly becoming possible. Extend these trends decades into the future; are you okay with a world where people can select the quality/type/number of organs for other people? What about the intentional creation of deadly viruses that select for subsets of the population? What about organizations intentionally modifying embryos to create people fit for menial labor? What about people making involuntary clones of others? And so on and so forth with the presently sci-fi topics.
Whether or not most people would generally agree to do such things, the fact is that they become possible. Without accurately projecting the economic factors in play 50, 100, 200 years from now, you can't actually confirm that people won't exploit biological research in this way.
Consider the atomic bomb as a case study. There are immediate positive side-effects that particle physics has brought to the world; but it doesn't simply cancel out the negative effects, nor can anyone alter their severity. After the creation of the 1st atomic bomb, the world is now left in a position where any of the major world super powers can _literally_ wipe out all human life on earth. Millions of man-hours per year have to be dedicated to preventing terrorist groups from acquiring atomic weaponry, and the stakes of political action have been permanently raised.
Similarly, if producing viable human-animal embryos becomes possible, the status quo of biology is permanently altered. Is it for the better? Maybe, but it's glib to just _assume_ it's better.