I agree, "Rare" is a misnomer as far as % of the upper crust or even full-scale scarcity, but the big pain in the ass is that they are spread all over and most land that they could be found on/in is already claimed or under control by someone else. That and the process of mining them tend to be somewhat regulatory and cost-prohibitive in the US. This is also why Greenland is such a talking point; a huge landmass and little red tape to mine them.
The projection in 2020 was that Ukraine would be the 2nd largest producer of REs by 2030 in the world... Not so much now..
I think from a mineral richness standpoint, the value really is that 1/3 of Li for Europe and the Middle East comes from the Ukraine, same with things like Graphite, Titanium, and Uranium. Add into that the RE's and financial and geo-political "value" is there, even before the basic common sense of not letting Putin and Russia expand.
Every move being done now is not with an eye of corralling Russia initially, but limiting China. In many ways, the current geopolitical strategic thinking for this (and to some extent the last) administration is that the Cold War has shifted from Russia/US from out childhoods to China/US and we need to approach our viewpoints with that shift in mind. We have to accept that it is viewed that Russia is no longer the greatest threat to the sovereignty of the nations of the globe, and though the invasion of the Ukraine is horrific and barbaric, all moves will be done with limiting China in mind as well.