WB has finally learned...
or, they know they have a good movie on their hands this time.
Critics have to be pampered; they have to be treated as royalty, they need to be given privileges. Things like early screenings, throwing a party for them, having the filmmakers interacting with them, etc. are good ways to do it. That's PR and it's very important.
Why? because they undoubtly impact a movie in a positive or negative way. You can hate them and discredit them all you want but it is undeniable that a critically acclaimed movie will draw people's attention, whereas a panned movie will make people lose interest. As a business, you want people to be interested in your product.
If I remember correctly, they hid BvS from critics till the very last moment and that was a mistake. Sure, BvS was never going to be critically acclaimed, but giving critics some privileges could have at least mitigated some of the backlash. They were embargoed anyway so I don't think they would have hurt the movie's OW. At the end of the day, they're humans and can act based on their feelings and emotions.
I believe Disney-Marvel does it all the time, but it's not hard to tell they are a better run company.