With regards to the Filene's site, this is simply not what happened. The construction lender got vaporized in the credit crisis, and the financial sector of the entire planet was in "run and hide and curl up in fetal position" mode. Absolutely no construction lender could be found for a while, and during that while, it looked for a few months like the meltdown could spread to the entire economy. Ergo office space rents were dropping as businesses retrenched. By the time other construction lenders were willing to look at it again, the numbers didn't make any sense. That one got caught in the worst global downdraft any of us are ever likely to see (I hope), if that had all happened when it was half built, we'd have seen it sitting there half built for those years, instead of a crater. Better for us all that it fell apart at the hole in the ground stage, that made it possible to move on to what did happen.
There's every chance we'll see one or two other sites go into mothball mode in the coming years. If the approvals process were faster, it would just mean a different set of sites would go into mothball mode at each recession.