Currently the game does not "take away" any of those remote resources you send your Pioneers to. Nor do you benefit from those resources until they fall inside the actual min. distance from a Town, currently 4 Tiles I believe, so it makes it hard to actually tell what "costs" will eventually be incurred to take and hold those remote resources.
Thus the cost of Pioneers may be quite high if you find yourself near an aggressive neighbor who thinks those resources should be his and not yours. (assuming we can "take over" a pioneered remote resource of course) 
So here is a possible compromise.
If I build a City, then any resource tiles within its min. boundary consume only 2 tiles, and any Resource that a pioneer is sent out to, outside the min. tile # (as is now) will consume 4 Tiles and always consume 4 Tiles, even after your nearest City eventually either snakes out to it, or you drop a new Town, thus placing said Resource inside the min. boundary of the new Town.
Otherwise, be it a smart AI or a another human player, running out with pioneers to hold a resource, until a City can be dropped, just to milk that resource, could become a do or die strategy.