It's not depressing, it's the nature of the beast. The MTA spent over a billion dollars and toiled for 10 years before its first CBTC implementation went on-line. It's fundamentally that much different than an ATO or trip-stop system. 80% of it is in the central dispatch back-office...software, server racks, debugging, dispatcher training. Very little of it is out in the field...just some cheap little RFID transponders on the track for maintaining unbroken radio signal, the fiber optic cable those simple transmitters are hooked up to, and the computer receiver on the cars. The systems they replace involve hundreds of miles of heavy copper cable; power-sucking electrical feeds that burn thousands of watts per day; on the mechanical systems like NYC literally thousands of signal lights, trip arms, and switch heaters; and on ATO systems like Red/Orange hundreds of magnetic induction boxes and track circuit insulators.
All of that maintenance-intensive trackside metal and electrical that you can see everywhere out the train window gets displaced by a server farm in the central operations center that you never see. It's trading way, way less complexity trackside for way, way more complexity at the nerve center. So of course it's going to take forever to design and equip the nerve center. The upside is that once the nerve center is scaled up it gets a lot easier to do the field work and equip the cars quickly, orders of magnitude easier and less-costly to keep good SGR out in the field, and each additional line you equip goes faster and cheaper than the last. But it's an enormous change in skew; everything out-of-sight gets front-loaded and gobbles up lion's share of the schedule, while everything trackside is done last and quick. It's totally, absolutely different from how signaling works today. And that's why it can't be timed with a car order.
It's not good/bad/fast/slow...it's just different. If they got the ball rolling 5 years ago they'd still be in the same place NYC was: wads spent, but no trains running on the new signals yet because the nerve center you can't see chews up the lion's share of the project schedule. These new cars would still have to run for their first couple years on the old signals even if they acted more proactively. It's that different a construction schedule.