For normal member markers, probably not. But for all other kinds of markers there is indeed a very big need to zoom in on the exact location.
When a member searches for location, Community Map will get the full address in return. What I could do is execute a new search but only with the postcode and city. That would in some countries not pinpoint the location. But I'm not sure if this would work in London, for instance, where I believe almost every block have its own postcode.
User enters: "My street 123, 43234 City", Mapquest will then respond with almost the same address, maybe they've added a region to it, but I could then do a new search for just "43234 City", removing the address line(s).
I would also like to say that we are all responsible for our own security and privacy, and this goes for all your users as well. If they want to publish their full address on the internet that is their own choice, and you can't say they haven't done it on purpose.
Immediately after they've added the marker they are taken straight to the location they just added, and if they are not happy with the position of it they are free to delete it or update it.
That is one of the reasons why I'm not adding a GeoIP feature that'll automatically put people on the map.