this is kind of the natural ebb and flow of business, i think. first, you get a small-ish group of people (the hardcore gamers) that buy games and love em. but then, as a business, you need to grow. so you start catering to more "casual" gamers to sustain your business. thus, you have less time/resources to devote to the hardcore crowd. sure, hardcore games will never go away, but there will be less of them.
a bit sad for hardcore gamers... but business is business. although an interesting question would be, would hardcore gamers pay a premium for games that they would like? for example, many movie-goers pay more for art-house theaters to see really good, non-mainstream movies. it's at a premium, but damn the movies are good. would you pay $100 for another Fallout, or System Shock, or FF6, or..X-Com? hmmm...hell, i would. i'd much rather pay $100 for a modern System Shock than $50 for the watered down BioShock.
maybe it's time that games develop a premium market.