boon for humanity
2015 RR245 will be closer to Earth than Pluto years before the moment of closest approach to the Sun. We'll be able to send probes there within the next 5-10 decades.
Finding an unexpectedly high amount of largish dwarf planets is a boon for humanity. We may eventually reach a point in technological development where we could live indefinitely on places like Ceres, Europa, Pluto, Sedna, or 2015 RR245. If Planet Nine exists, it will probably have some satellites we could live on as well.
"I don't want to live on a small. cold rock," you protest. Well, maybe it won't be choice. Just kidding, it really depends on the commute times between Earth/Mars and these distant objects. If 15+ year travel times could be cut to months or weeks, it would be much more tolerable and comparable to crossing the Atlantic or circumnavigating the globe centuries ago.