This might not be relevant to users in very safe countries, but if you live in or travel to some South American or African countries (or even in some districts of the US), you do not necessarily want to get the fastest route, but the SAFEST one – omitting dangerous areas (like gang zones). As a concrete example, I was driving through Rio de Janeiro and Waze suddenly tried to reroute me through a Favela, because it was supposedly a few minutes "faster" (something, travel guides and the State Department even explicitly warn about). In fact, there were already news reports of a women who got shot after trusting Waze leading her into the wrong (gang-controlled) street in Rio.

Therefore, I suggest that Waze either generally omits routing through certain areas (as long as your destination is not located there) or at least warns you if your chosen route goes through such an area (as it does with travel / zone restrictions). Most importantly though, Waze should not automatically reroute you if you have purposely chosen a certain (safe) route, just to safe a few minutes, without your consent (or absent dissent), such as Google Maps does it by letting you reject any rerouting. This might actually save lives in some cities.

(I know that there is already the function to report "safety incidents", but this precaution should be more proactive / preventative than reactive.)