Big MT and the research there actually had a positive and well defined purpose in the world before the war, where it's hard to imagine crafting an AI menace and teleporting replicants was going to be beneficial to mankind..
How is creating a robotic workforce that never needs to eat, sleep, and can run forever with basically no oversight, unlike the retarded Protectrons and Mr Handy bots, NOT useful to the pre-war world which was incredibly lazy, highly consumerist, and largely relied on a robotic workforce to do everything for them anyways?
They already had controllable robot helper monkeys everywhere, and from all of the in-game lore they were plenty useful and didn't need a lot of oversight as long as someone programmed them correctly. They ran forever, did their jobs and didn't THREATEN HUMANITY.
They didn't need this AI replicant idiocy, and it was actually detrimental to the purpose of having a 2nd class of mechanical helpers.
Creating a slave population only works if they don't know they are slaves, so giving them AI is just plain stupid.
Doing so would be setting yourself up for absolute failure, and spending a bunch of resources and time just to do so.
Just because Bethesda says a bunch of autonomous robots would be the perfect workforce, it does not a fact make.
It's just a stupid idea from so many angles, and when applied to a world that already had a better solution (non-autonomous robot workforce) it makes very little sense other than as a progress for the sake of progress concept. (which is as inherently flawed as their writing)