RamscoopRaider
Donor
The goal of the Constellations was to have a proven design fast and at a reasonable cost, redesigning to cram in an extra 16 cells would take time and money that detracts from both and increases the risk of no frigatesI'm almost certain the batch 2 and likely beyond (because if the USN actually just buys 20 instead of a lot more than that I'll eat my metaphorical hat) constellations will have those extra cells. Why they didn't have it as part of the design requirement from the word go beats me. Same with having that small of a main gun. 57mm is way way too small for a ship of that size.
Tying size of gun to size of ships is foolish, people could say the same about 5" as a main gun caliber for a 6000 ton ship in the 50's. 57mm has a low manning requirement and can fire smart shells for supplemental missile defense, in addition to warning shots/potting drones. 76mm does not offer that much more range for potting drones and requires more crew/weight and the USN has phased it out, 5"mm offers noticeably more range and shore bombardment but is much bigger and more crew requirements. Given low manning is a priority for the design 57mm is about perfect