Because literally, the entire quick food options in the area include:
B.Good
Chipotle
Clover
Dumpling Daughter
Cava
Au Bon Pain
Bailey and Sage
Sebastians
and those last two close early.
Meanwhile we just keep adding coffe-shop after coffee-shop and it is not even clear there is demand for this many.
There are almost no late-night options. And then people wonder why this area is so dead.
We already have Eastgate, Watermark East, Watermark West, East Campus, Senior House, 100 Memorial, 3rd Square, and two hotels all right in this little area, and now we have Proto. That's gotta be over 2,000 people. People live here, and even more people work here. I don't think the problem is that we need more people here.
I agree this is a curious case study in placemaking (and associated activity/energy/patronage), but I can't quite put my finger on what exactly is going on. MIT polled grad students (of which there are ~6,000...probably at least 1,000 of which live in/near this area (vs. west or off-campus)) about quality of life issues in 2017, and one of the themes from survey responses was the need for easily accessible, affordable, quality late night food in this area. So clearly the perception of demand in this area is not limited to Gameguy326's.
Then, MIT partnered with Rebecca's Cafe to open a late night dine-in or take-away cafe (open till 1am)...but they buried it inside an obscure 2nd floor corner of the Walker Memorial building and no one ever went to it. The offering wasn't fantastic, but it was solid and the prices were part-subsidized (I believe) so affordability wasn't the issue. They even tried to give it some character in terms of interior design.
Regarding coffee, I'll respectfully disagree that we're saturated there. I'll certainly agree in hoping (seemingly as much as you do) for better quality late night food options in addition to coffee. But there's rarely a seat to be had at that corner starbucks most any hour its open except maybe early morning. Assuming they're profitable with those types of grad student dwell times, I'm sure more capacity across the street can be accommodated...especially if the Blue Bottle stays open later. Meanwhile, I support good-old-fashion competition in terms of quality...if Vester's offering sucks, let someone else try to challenge them. ~3-4 coffee shops in a student mecca is nothing. Have you ever been to the Telegraph Ave. area in Berkeley?
There are a couple of mid-tier late night offerings you're missing: Champions at the Marriott, the bar at Legal's, the Black Sheep at the Kendall. I know you were listing quick-bite types, I am not defending these places / saying they are great (or affordable)...but I bet there is some overlap in terms of candidate customers that go to them. Including the hotel guests you mention. So it is probably fair to add them to the mix.
So I'll get back to my initial point about lack of "place"...you've got a sizable, but fairly diverse and disparate customer base here. There's no discernable hub of activity yet, and the various people that are here are spread all over. I think that's part of the issue.
But I think all of that really will change with the Kendall Gateway projects. The Main/Broadway intersection will form a hub, with a whole bunch of new ground floor retail / two types of markets / lots of new residential.
That said, I wouldn't mind seeing that Ames St. stretch become more of a late-night zone. Doesn't Proto have at least one more retail slot beyond Blue Bottle/Cava? And maybe Vester will turn over like hypothesized?
All we can say is that these are very dynamic times for this area.
