This is exactly the point I was trying to make.
Yes, but it appeared as if you applied that point unilaterally to a discussion about having ectoplasmic construct bodyguards tied to a ward, which differs from the "Superstar NPC Ally" in two key ways:
1) the constructs and the AI overseeing them aren't in a position to do everything the player can do, only better - they are focused on fighting intruders, and presumably, the player is better at magic
2) the constructs and the AI aren't in a position to replace the player - they are geographically tied to one spot, watching the player's stuff
And even if the OP wants more out of their AI, having the ectoplasmic equivalent of a supercomputer running one's house has plenty of narrative conflict potential (can the AI be mind-controlled and turned against the maker? let's find out!), and numerous fictional analogues (though SYnergy, the AI from "Jem" is the only one coming to mind at the moment).