The problem is that writers don't understand what a cliffhanger is. A cliffhanger is not when you simply fail to provide a satisfying resolution to your movie or game. That is just a shitty movie or game. It is not when you make the same story drag out twice as long as necessary during the sequel. A cliffhanger- on the other hand- is when you provide clues or exposition about action to come after the very extremely satisfying resolution of the story I'm involved in right now.
In short, the problem is that dumb-dick writers don't know how to write stories properly. Look at HL2:EP2 for an example of a decent cliffhanger. The new information you are presented with is the makings of another completely different story. If it were written by dumb-dicks, then Gordon would have failed to accomplish [his goal], and would resume trying to accomplish the exact same goal in the next game. This is what shitty writers confuse with a proper cliffhanger. Like the ending of Halo 2, for example. Shameful.