City Attraction gives a better effect on a player's preference in living when joining a new club.For example:
London is an urban,metropolitan area,with transport,good links to clubs and good state of living.Clubs like Chelsea,Arsenal and Tottenham would have good chances of attracting players.
Say,for example,a countryside (dunno what city/town) had a club and they wanted to buy a player,his preference may not be in quiet countrysides,but urban areas.It plays a huge part.
It will even say sometimes when a player changes from a rural to urban environment.