I think the point is that more of the audience than ever seems to have this critical eye, not that it didn’t exist before. With the world becoming smaller and information becoming available to you literally at your fingertips, more people are able to find out more backstage information and break the fourth wall a lot easier. One big difference now I think is that with the expansion of the hardcore wrestling audience because of the internet, message boards, social media, etc., is that people don’t quit on wrestling the way they used to. In the mid 90s the WWF struggled financially because the product was bad so people stopped watching. Now there will always be a hardcore fan base who will always watch WWE, but will also criticize (justly a lot of the time) the product in hopes that it will become better (which by and large it probably won’t).
I’d say that the fans are just as vocal as in previous eras, but instead of a letters to the editor section in a wrestling magazine all feedback is almost instantly thanks to the internet.
Also it’s to do with word of mouth, if something bad happens most likely five people will share compared to if something Good happenstance.