It doesn't make sense to me that a state court should be able to issue a nationwide injunction.

And what's burdensome about it? (Now, a case could definitely be made for it being stupid duplicated effort. Every year I'm annoyed with FinCen over having to file a form about foreign accounts--almost all of the information also appears on our tax return. However, it's a minute or two of cut and paste once a year, no great burden.)