This was likely a Business Decision

[FuzzyPlum]

I would have gone as there was some discussion of them digging out deep cuts/older songs. That would have freshened up the setlist.
I'm not sure to what extent they'll be able to do that now. They need to keep it as identifiable as Fleetwood Mac for casual fans as possible so Chris and Stevie will most likely stick with their must do's.

Regarding the double tour- it may have generated additional publicity so it could have benefited both Lindsey and FM in terms of ticket sales.