We seem to have got a bit off message, the premise wasn't whether Playmobil is targeting children, of course it is, but whether it is aimed at getting those children to play, or to collect.
A visit to any toyshop these days, or pretty much anytime in the last century, will show that some toys/games are intended to form some sort of collecting addiction. Take Topps Baseball Cards. There are games you can play with baseball cards, but mostly people buy them to try to complete a set. If you complete the 2008 set, it doesn't matter to the manufacturer because soon you have to start on the 2009 set.
I think Playmobil bucks this trend, because although they do keep refreshing and adding to old themes, such as the knights or pirates, I don't think this is so that children keep buying moree and more to try to complete a collection.