I get that, and carriers are definitely stupid. But preventing people from gaining SS7 access is much easier than fixing a broken protocol in use by many device

I get that, and carriers are definitely stupid. But preventing people from gaining SS7 access is much easier than fixing a broken protocol in use by many devices. Blocking SS7 access is something carriers can do. Fixing 2G is just not possible, and anyone can break it, right at this very moment, with a tiny bit of hardware.