The Core set is a tiny little fraction of the whole game...
Um, it's actually a whole game. Many people buy the core set and enjoy gaming with it and never buy a single expansion.
I have most of the LCGs core sets but only one (LotR) that I have everything for.
I sometimes wonder if it wasn't so expensive (multiple core sets) to really get into deck building right from the start if maybe more casual players would start buying more of the expansions?