First off: slow? They developed several new versions of Advanced Power Armor, finished an aircraft prototype, a plasma prototype, and continued various other government projects.
Second: Its not just the Enclave. House, founder of Robco, is using Securitron bots as his mainstay, and they aren't anywhere close to Androids that can freaking poop. Nor does Big Mountain or the Brotherhood have anything close to it.
My counter to that is that the Enclave, and other technologically advanced factions, are advancing their technology at a rate that makes sense within the context of the Fallout world and the post-apocalypse. Everyone is pretty much on the same level in terms of their own technology and how quickly they are progressing.
The Institute however, is lightyears, lightyears ahead of everyone, barring Mothership Zeta Aliens.
That's a problem.
Honestly, I don't really care whether or not its "possible" given 200 years that a single technology Institution could create androids of that caliber. It doesn't fit within the context of the Fallout world and doesn't match similar technological developments on a reasonable scale. Its out of place.