Re: Trans National Place (Winthrop Square) Part 2
It's not really true. What you call "dense, completely uninterrupted development running all the way from SF to the South Bay" is actually a 4-mile wide strip between 280 and the Bay. And it isn't "dense" - within that strip it's Newton at its most dense. West of 280 it's Carlise! San Jose itself, meanwhile, is large but is also towers-in-the-parkish.
The problem with assessing the size of the Bay Area is that yes, it's fairly dense, but it also spreads over a huge area along narrow corridors due to geography. Boston's metro is a cohesive area, but the Bay Area spreads around all different sides of a tremendous bay, with parts of each side somewhat akin the I-95 corridor from Stamford CT to New Haven.
The geographical factors are important, but I don't see why that makes the connectivity between SF and SJ any less real - or the connection between Boston and Providence any more real. The question is whether the 7.5 vs 7.4 million numbers are comparable as metro areas, and this turns on whether Providence (and Worcester, actually) should be included. So if you're trying to make the argument that Providence should be part of the "Boston metro", you need a certain amount of density in between the two, not merely some percentage of commuters from the Providence area driving into the Boston area. In the Bay Area, it is unquestionably the case that you have this density, even if it was "forced" by geographical constraints. In Boston, you reach the exurbs out in Foxborough before you get to Providence. If you had Newton/Quincy all the way down, it would make Boston and Prov way more cohesive.
Newton is 4600 /sqmi, while standing between SF and SJ you've got South City (6700/sqmi), San Bruno (7400/sqmi), Millbrae (6400/sqmi), Burlingame (6500/sqmi), San Mateo (7500/sqmi), San Carlos (4700/sqmi), Belmont (5500/sqmi), Redwood City (3800/sqmi with huge marshes in city limits), EPA (12600/sqmi), Palo Alto (2500/sq mi - half of the town is preserved land), Mountain View (5800/sqmi), Sunnyvale (6000/sqmi), and Santa Clara (5600/sqmi), and Cupertino (4600/sqmi).
I understand that it's all geographically constrained California suburban sprawl, but it's decidedly suburban all the way, whereas 495 territory is pretty clearly Boston exurbia. You definitely pass into a "different metro" when you hit Providence.
Plus, from a non-built environment standpoint, the incredible amount of "reverse" commuting to Silicon Valley from the City and East Bay is probably a better argument for a Bay Area MSA than anything.