studios and screenwriters think they can write comedy now. Back in the day you just wrote a regular film and let the comedian handle the funny bits via adlib for the most part.
Beverly Hills cop was originally a Stallone movie, but then they casted Eddie Murphy. it wasn't planned as a comedy. he just made into one.
That's not how comedy works anymore though. They'll just cast regular actors like Chris Hemsworth and try to have a funny writer or director write the jokes for him. Thats why modern comedies suck and why comedians aren't becoming huge movie stars anymore
What happened with the scary movie franchise being taken from the wayans and given to Charlie Sheen was basically the turning point.