It's been a full year since the first vaccines were formulated, and it took the FDA 11 months to give the OK. That was a large streamlining of their normal processes, but not a meaningful balancing of risk, the standards remained the same.
In the meantime, the virus has had millions of opportunities to mutate like this. If we'd accepted a bit more risk, we could have significantly decreased its opportunities to mutate.
At least in this case, the virus can't mutate faster than our ability to formulate a new vaccine. Whether we can retool vaccine manufacturing I don't know. But so long as the FDA won't allow us to react quickly, the hole we're in keeps getting deeper.