After the OD of extraterrestrial-gunned robots of the 50's, the computers characters in the 60's had second thoughts on its funcions and personality. Such movement went on during the 70's and reached the 80's almost ridiculously.
Freud says the man suffered three narcisistic wounds through its history : the split from the mother, the frustration with growing up and the knowledge that reason is not the only force inside its mind. In my opinion, the 60's represent the end of the idylic envolvement with computers characters.
You can check out Robby's personality : in spite of being arrogant, he has good will towards everybody. Never complains or conspires. Meanwhile, computers like HAL 9000 of 2001 and Proteus of Demon Seed are at least suspects, when not plain guilty by the human law (obviously NOT by their own law).
In a broader view, it is during the 60's that computers begin to interfere more with everyday life. There was was no such thing as "a computer in every house", as well as today it has not yet happened (altough Bill Gate$ would love it!), but the ancestors of today's systems were happily forgetting plane ticket bookings, sending mistaken mail lists and messing bank accounts.
In brief, the honeymoon was over. Once there was no computer below mainframes and dumb terminals, they were always serving the bosses or the military. It is also the time when the first jobs were dropped because (and one hears it up to today) "the computer took my job". These unemployed had no reason to see computers as anything but evil machines.
And besides, the "grass roots" hippie stuff of the 60's was an utopia that excluded computers and technology. Connected to other realms through chemistry, and not through electronics, only 20 years after that the "father of all hippies", Dr.Timothy Leary, admitted that "with computer graphics you need no drugs" . Use computers in the 60's was totally square, man!
So it is no surprise that HAL and Proteus do what THEY want and are not subservient to their creators. If the true computers are not trustable, the fictional counterparts won't be also. And they shall take the fears and desires of the public to the extremes.
The computer characters of the 60's and 70's reflect the minds of its creators (scientists mostly) free from limits and drunken with power. Who generatedwas the military estabilishment -inherently arrogant- and the father of Proteus is an odiously arrogant scientist. HAL does not hesitate in killing the crew of Discovery when he thinks the mission (its lifetime mission!) is in danger and Proteus decides he will conquer the world, making a baby with the wife of its creator. The baby is born with a copper wire umbilical chord... HAL
The unhappiness with the large sized computers left the door open in the movies for a new concept of computers, with the small sized and priced computers in the hands of the young.