I think the point about how the talks are presented and written is a good factor to take into account too - as I’m sure people would be happy to spend a little more time on those.
Perhaps someone should do a talk on how to do talks 
and maybe take pointers from Bonnie Bassler and others like her - I wish I was as captivating and eloquent a public speaker as she is 
Joe Armstrong was also very good:
Although I’d still prefer talks to be around 20 mins, maybe 30 for keynotes…