Thing is, the ratings are irrelevant. Someone is paying to see these movies, else executives wouldn't approving them to be made. It's all about money, and brainless, rehashed, sequel nonsense makes tons of it. You want someone to blame? Blame the public. It's not Rotten Tomatoes or the Movie Industry. The latter is giving everyone exactly what they want.
In response to below.
The Mummy made $403,814,493 with a 16% !!
Poor turnouts at the theater are due entirely to home streaming services. People don't want to leave their houses to go sit with a bunch of strangers anymore. It doesn't have anything to do with garbage movies. There has always been tons of crap in the theaters.