Because,in their opinion, the disadvantages of a separate currency outweigh the advantages. Unlike other "independent" analysis they do not present the details of their analysis of the pros and cons of the various options * which is why AS is in a bit of a pickle at the moment. He has not prepared answer to this.
Like yS, the FC is laying out a clear argument against independence. Stiglitz and Mirrlees are both leading academics and practioneers in their fields including tax policy (Mirrlees). So they know that their proposal means that in effect Scotland continues to cede control over interest rates, money supply, levels of tax and spending to those nasty folk in Westminster. However, this time, they will have lost much of their representation (if not all) in the decision making process.
Unlike the FC, The Brothers continue to lie saying that you can have the benefits of both your own currency (see lists a few pages back) AND a currency union. Complete deceit.
* I find this very odd and unhelpful (until you remember who is paying for the work!!!)
Ben, you are kidding, I have been married 22 years!! and remember the words of the Scottish government
The Scottish Government is clear that post-independence it will always be up to the people of Scotland, and their elected government, to decide what our currency should be.their website intro to the FC report.
We say what we want, stuff what the rest of you think. Comments echoed by wee eck in the past 24 hours. Very compromising.