It's pretty ridiculous isn't it. After the Harry Potter films and more recently Hunger Games and Twilight have spawned the novel into film craze, where most of the output is pure crap.
Fox is pretty much directly responsible for two such failures in Eragon and Percy Jackson, but at least Eragon didn't have a sequel made.
In both those efforts there was the same blatant disregard of the fanbase who made the novels so popular, and resulted in films that neither the fans wanted nor the general public.
But cheap studios like Fox and Lionsgate have figured out how to scam the public in producing movies on a TV show budget and getting a huge rush of the fanboys/girls to put money in it on opening weekend but then see the films quickly die off. Not all have been as successful as Twilight and Hunger Games in that regard, and Hunger Games is unique in that it's actually a pretty good story with good acting and actors like Jennifer Lawrence who they never would have been able to afford if the films were being made right now.
Twilight is the ultimate success in cheap film making. The first film was made on $37M and it made just under $400M WW. Only the last installment had a budget over $100M and the last two chapters were filmed simultaneously, so the budget is a bit over inflated because it was spread across two films.
It's not going to surprise me if they continue with sequel plans even if this film bombs, but with as much ill will as this film has it will be double that for the next one.