They care in the UK because they want Scotland to remain part of the union, mostly for their oil. Scotland has huge oil fields, which were opened up by BP and pipelines built to bring it ashore. The revenues went to London. If Scotland does secede, then they will be regaining control of their oil resources. That is 1 reason.
I remember hearing years ago that if Scotland were an independent country, it would be one of the richest in the world. There is another reason why they want independence.
I guess it is not important at all unless you live in England or Scotland.
If they vote for independence, then independence they shall have. It is also interesting to observe the vested interests and serious money throwing their weight behind the No campaign (no to independence).
If i was Scottish, I'd take one look at who was behind the No campaign and run to the Yes side.. but that's just me.