The original release just didn't have enough content to warrant a price tag - you could get a (non-death) ending in 15 minutes if you know what you're doing, and even 100% completion requires you to pretty much play that same 15-minute window of content over again until you find everything.
Fresh Ingredients, on the other hand, easily has an hour's worth of content, even if you don't count secret hunting. $4 for an hour-long game is not a bad price at all.