Just make it up to fit a preconceived notion? No data needed? That seems to fit the way business is done these days in the .coms as well as in politics (hasn't it always been that way in politics?). Funny thing: companies are collecting zettabytes of data about all of us to use in targeted advertising, but little seems to be done to support rational planning - maybe because "rational" doesn't sell and isn't "internet-speed" - it means that you're thinking about it not just doing it.

Unfortunately, actually building something take real time and real money (and puts real people to work - construction seems likely to be one of the last industries to lose labor to automation). So building something can't be "agile" or "internet-speed" leaving many people to ignore it as they go on to the Next Big Thing. And it also means that you need real, data-driven planning and engineering and long-term funding (not "seed" funding from a Vulture Capitalist, which is roughly what CAHSR got then spent like a tech startup) to ensure that what you're building will actually serve some purpose (maybe not its original one) by the time it's finished in 5-10-15-50 years.

My view: ACE is a good system now. It serves a purpose, at a relatively low cost, by sharing facilities with a freight railroad. It isn't (and can't be) a BART-type service both because of demand (commuters - and are the trains standing room like on peak-period Caltrain?) and facility (only so many spaces between freight trains). So don't try to make it what it isn't. At most, perhaps, if Dumbarton ever is reopened (show me the $$!), a couple of trains could be added or rerouted to meet Caltrain for transfers to elsewhere on the Peninsula and in SF. No matter what, I don't see a huge crowd (short of a HSR connection making the travel time similar to BART time from the near East Bay) doing the Modesto/Stockton/Tracy/SF commute (50 people using a Dublin shuttle? Does that justify a direct BART or Caltrain connection, really?), and ACE shouldn't be chasing that when they have good ridership now. And if things change so the SJ commute is no longer relevant, ACE hasn't required a huge sunk investment so it can be revised or shut down/sold off without a lot of hassle.