Propagates the common error that "long half-life" = "more dangerous", when, by definition, "long half-life" = "not very radioactive".
Chernobyl and Fukushima have been interesting studies in what low-dose long-term radiation can do to ecosystems (not much? things seem to adapt ok), but we should still take what precautions we can and not just irradiate things willy-nilly...
It's like the way that no one gives a crap about the natural oil seeps off the coast of Southern California, which dump about 5 million gallons per year right into the ocean, then they have a panic reaction when a boat accident dumps a couple of hundred.
Likewise, some slow underwater seepage probably just gets washed away? But if you add a whole bunch of oil on a seashore that normally doesn't have much, it'll kill a bunch of cute animals and make your PR team have to work weekends.
If you drastically increase the background radiation near a suburb by piling spent fuel near it, the residents won't scientifically analyze the risk, they'll just try to keep you away. If you try to build a new plant, every politician within bribing distance of some special interest goes haywire.
Yucca Mountain might've been an option but that got shot down too.
A mix of precaution and NIMBYism, some of which is good science, some of which is just junk politics, and much of which is just people being primates. We're not evolutionarily equipped to make these sort of large scale long term decisions, only to live and die by our tiny, intimate lives.