What's the benefit of Hollywood still using film for most major productions?
Is this an impression you have or based on statistics you read? My impression is the opposite: projects shot on film have become so noteworthy they get some press coverage for the fact alone they are shot on film. Then you have things like "interstellar" where the hype was about the 70mm or tarantino who says movies on digital are not sexy. What I heard is that unlike 5 yrs ago, the predominant tool in feature film has become the arri Alexa, while RED is going strong in advertisement. From the distribution side I know that (in Germany) the big multiplex cinemas don't have 35mm projectors installed anymore - they set them up on demand - and that at big film festivals like the berlinale, the amount of analog prints has changed from 9 out of 10 to less than 1 out of ten over the last ten years. Apparently it has become difficult finding a lab that can develop analogue film (in Germany) nowadays. 

The reason for people still using film is probably that film automatically adds a lot of organic texture, like minor irregularities, grain etc. that a lot of people aesthetically prefer and which is not easy to mimick digitally in post-production. Using the "original" material also is a tribute to the history of the craft in a way... Going analogue all the way, even in editing (which is really not done anymore I think, even with the biggest fans of film stock) takes you back to a process which is actually destroying something (making a cut) to create something new, so there are some powerful metaphors in the original process ;)

Products like Blackmagic cameras are not used in big budget productions because the quality assurance, sensor quality etc. Is not up to par with cameras by arri or red. And for productions on an average Hollywood budget, the difference between I.e. 5000$ for a bm camera or 60.000$ for an Alexa is not really relevant, especially since a flaky camera ruining a shooting day can result in much higher costs.