Over the last few years, there have been shifts in the industry.

In the beginning of the millenium, Spiderman became huge, and its success which completely revolutionized block-buster superheroe movies, which we now see a couple of times a summer, spawning everything from batman reboots, ironman, and all the little ones like watchman, green lantern etc, and probably can be credited for things like transformers.

Knocked up and forgetting sarah marshall can be credited for a new genre, the male oriented romantic comedy.

And believe it or not, twilight and hannah montana, from an industry standpoint showed that there is an entire untapped, crazed market niche called tweens, which is now growing.

In general, the previous, and other film successes such as the proposal (and sandra bullock in general), mama mia, bridesmaids and even SATC, and in general the dip in theater attendance by large action bangups, are all indicative of trends that the most profitable demos are no longer the male 18-40, and you might see a shift in where films will be more catered to tweens and older people, esp women.

TL;DR even if bad, twilight is changing the industry