Please show these studies that show creativity is down. You can't say movies from the 80's/90's are objectively better than movies from the 50's/60's, everyone has differing opinions about the art form.
Also, YouTube does not represent the world, chances are these Youtube channels are built around exploring old movies which would not be the general populace. Just ask your kids or nephews/neices or friends kids if any of them care or anyone from their school care about movies from the 80's/90's.
Proof that 15% of movie goers are teenagers?
Even if a mid tier film fails at the box office, it's still making money that it wouldn't have made if it went straight to streaming or DVOD.
Just look at the failure that is The 355. It's budget was between 40 and 75 million dollars and it's box office was 28 million.
https://www.boxofficemojo.com/title/tt8356942/?ref_=bo_se_r_1
https://www.the-numbers.com/movie/355-The-(2021)#tab=video-sales
If they released this directly on streaming or DVOD, that's 28 million they simply wouldn't have made and it would have been an even bigger miserable failure for the studio.
Movies never make anywhere near the same amount of money on the home market compared to the box office. Just look at Iron Man as an example which released around the time that streaming started to happen.
https://www.the-numbers.com/movie/Iron-Man#tab=video-sales
It made over 500 million in a significantly short time frame at the box office and then made nearly 200 million on the USA home market. The home market took 10+ years to achieve those numbers though. Other countries home market sales would be significantly less than America just based on population.
Then look at a modern smash hit, The Batman.
https://www.the-numbers.com/movie/Batman-The-(2021)#tab=video-sales
767 million at the box office and then a measly 10 million on the home market. Yes, digital sales will make up a bit, unfortunately we don't have those numbers but I can guarantee it didn't make 700+ million in digital sales.
Look at The Lost City which released this year. a mid tier film with a budget of 68 million.
https://www.the-numbers.com/movie/Lost-City-The-(2022)#tab=summary
It made between 180 and 190 million at the box office. Just 4 million on the home market, again, digital sales will be higher but won't match the box office. If it released straight to digital, that's 180 million dollars they simply don't get.