That has upset the National Federation of the Blind, which has been the public face of lobbying efforts to get a law passed. Automakers asked the NHTSA for the extra time because they aren't comfortable with the Proposed Rule as written, and a contingent of EV and hybrid owners have fought the ruling because they don't like having their cars make more noise – part of the appeal of said vehicles is precisely that they're quieter than normal ICE cars. In the meantime, carmakers are creating their own noises - or in some cases they aren't including any extra noise at all while they await the final rule - and their own implementations, some of which can be turned off, some of which are automatic.
Beyond the blind, the safety imperative is driven by studies that show that EVs and hybrids are 20-percent to 100-percent more likely to hit a pedestrian compared to an ICE vehicle. The counterpoint to those figures is that hybrids and EVs are less than two percent of the cars on the road, so even with the expanded likelihood we're still talking about tiny numbers.