Why do so many people complain about the ending...?

I honestly have no idea why so many people resent the ending of the movie... Is it the CGI? There was maybe one shot that threw me away a little (the close up on the alien's face) but I can live with that... Otherwise, it was a perfect ending. Every little thing we saw during the movie comes in place... Merril being a former baseball player, Bo's obsession with water, Morgan's asthma... It perfectly fits the movie's narrative that everything happens for a reason. And Graham eventually finds his lost faith. Perfect endind.