It seems to me that people are a lot harsher on movies now, less willing or able to suspend disbelief [1]. I see scathing assessments of sequels, but with examples of the imagined problems being problems that have reasonably close equivalents in their predecessors which no one had a problem with when those were released.

Here's a concrete example: probably the most commonly cited 'problem' I hear about Prometheus is that near the end of the movie the heroine "tried to run away from a wheel in a straight line", and therefore it is a bad movie. The general criticism I take from this is not that she took the reasonable general action (running away) but the specific course she took (running in a straight line so the wheel just followed, and not noticing it was following).

The thing is, I think that both the main previous movies in the series, Alien and Aliens, have comparable incidents which no one complains about.

In Alien, near the end of the movie when she was the sole remaining survivor, we had Ripley delaying her escape in the shuttle in order to scuttle the ship - an entirely pointless action. If her plan of escape in the shuttle had worked, it wouldn't matter whether the alien were still alive. What did she think it would do, learn how to fly the Nostromo and pursue her? Scuttling the ship both increased her risk of dying at the alien's hands (it could have easily snuck up on her when she was engrossed in the scuttling procedure), and also nearly caught her in the explosion.

In Aliens, we had Ripley delaying her escape with Newt from the processing plant in order to exterminate the room full of eggs which posed no immediate threat to her (especially those still in the egg sac). Further to this, she did not bother to spend even one bullet or grenade on the queen herself. Ripley expended virtually all of her ammunition on this task, not reserving any to cover her retreat, and she apparently did not bother packing a spare magazine despite being given the resources of a fully-stocked armoury when she was preparing to go get Newt. If she had not exterminated the eggs (pointless, given the impending explosion) the queen would not have had reason to personally follow her and cause all the subsequent grief. Needless to say, those problems could also have been averted by simply shooting the queen along with or instead of the eggs. Again, no one complains about this.

Note that I am not complaining about the above aspects of Alien or Aliens. I love both those movies, and think the examples I gave above are nit-picking. The thing is, I think the criticism of Prometheus is also nit-picking, and directly comparable.

My tentative hypothesis for this recent nit-picking is that, unlike the earlier movies which were from a pre-internet era, it is easy for people to congregate in online communities to pick apart inconsistencies in movies they were personally disappointed in, and then anyone who looks at discussions of a movie they just saw will read all of this stuff they might have otherwise just overlooked. Further to the particular example I chose above, lots of people were disappointed with Prometheus particularly because it was not what they wanted: another formulaic Alien or Aliens movie, so that gave them extra incentive to pick it apart.

[1] https://en.wikipedia.org/wiki/Suspension_of_disbelief