Let me be the first to say that you are blind. You conveniently forget that some other game developers produce way better games in a shorter timespan and gives the player wonderful hours of it without charging the player exorbitant prices.

I wonder if it were another developer, would you say the same thing or start flaming them for it.

To me, it does seem to look like Valve is milking their cash cow for all that it's worth. They have spent quite a number of years building the new engine and putting in new technology in such as hi-def and such, so why can't they use what they have built and produce good content with a good amount of gameplay hours and make it in to a longer game rather than breaking it up in to episodes. They're saying that Half-Life 2 took 6 years to make, which I believe was due to the engine, physics and gameplay mechanics, not content.
Now that they already have the base to build the content, why aren't they using it to make a longer game in a shorter time ? Most of the features are already in place (Object Oriented anyone), so all they actually need to do is create the story, design the gameplay, create a bit of new art, make the plot, etc.

Well the answer is simple. They want more money for less work. It's simple as that, and they will keep doing it as long as people like you seem to agree with their methods.

Let me ask you this question, would you rather pay $20 for one episode (How many episodes are there going to be ?) or a full game for $49.99-59.99 ?