I feel the same, and honestly don't know why leasing seems to be so tough. In fairness, I have seen Graffito do an admirable job with filling ground floor retail in certain places. For instance, I think 300 Mass Ave (Takeda) was done by them, and that came together pretty quickly with Roxy's, A4 Arcade, the running store, University Stationery, Pagu. Most of those are small/local business, and with a couple of them having somewhat of a bar/nightlife component (A4 Arcade, Pagu). Meanwhile, I truly can't explain the infamous 6-year-vacant corner slot next to Aveda on Main St.
At the end of the day it could really come down to retail rents being unrealistically high.
The thing I'll say about the Kendall Gateway retail though is, holy crap, that is a lot of retail slots to fill. I count at least 11 of them in the above marketing materials, not including the food hall and not including The Engine down the street. I really hope they're aggressive with this and in it for the long game in getting this filled.