Yes, you should care a bit about local crime. If someone in your neighborhood is stealing hubcabs, maybe it's a good idea to park in the garage. Likewise, if there's a spat of minor vehicle burglaries, it's probably wise to make sure your vehicle is locked.
Yeah, is some idiot going to theorize that the salesman who ignored their no soliciting sign a secret islamist infiltrator who is casing their house? Probably. That doesn't undo the value of the other things because silly people exist.
On the other hand, when there are bad things happening in your neighborhood like serious break-ins or joggers keep getting kidnapped, then you know, harass your local police department to step up patrols and act accordingly.
Crime as a whole lowering doesn't mean crime in your neighborhood isn't happening. Yes the world is getting more peaceful as a whole, but yes, you can still be mugged and killed.