Uh, how? They're getting 8 acres of land that's currently parking lot to redevelop and should make Washington St a vastly more coherent place, a better street grid, and a wider natural buffer for the sidewalk/bike path than currently exists.
What exactly were you expecting here?
They don't exactly sound opposed or like they were expecting any significant portion of the Arborway site to become park.
(Karen Mauney-Brodek, President of the Emerald Necklace Conservancy)
“This will be one of the most transit-rich spots in the city with more than 18 acres of public land that can be utilized in a way that meets community needs,” says Karen Mauney-Brodek, …
mass.streetsblog.org
So at "PVTA" square footage, that'd be 373k sf for 200 buses. This appears to include an underground employee parking garage, and that seems like it could be another 100k sf as well.
But really, if they're overbuilding the size of the facility relative to what they currently intend to use it for, I'd be thrilled that they're building facilities with room to grow further in the future, not opposed.
I don't see a budget listed here at all? Do you have one?