I agree with where you're coming from but I don't see it as being a vote about Scotland (from the wider UK perspective).
If the future if MY country is at stake (my country = United Kingdom) then I should have a say on that future.
Calling it a referendum about Scotland at that point is missing the bigger picture.
The SNP's move towards a Scottish referendum has simply acted as a catalyst for asking the BIGGER question to the WHOLE of the UK: "do you want YOUR country (the UK) to stay together or break up?"
That avoids the knee jerk retort: "it doesn't matter to us (the Scottish referendum)"
Of course the future of the United Kingdom matters to me, you and EVERYONE in the UK, ergo we should ALL have a say in it's future.
Simple. As. That