AI isn’t there yet. You could turn off AI tomorrow and there’d be a shock but people would quickly switch back. You could not do the same for electricity, medicine, combustion engines (or steam engines/turbines), computers, the internet, modern building materials, etc. You try to swap back off any of those and the modern world (literally and figuratively) collapses. Turn off AI, and there’d be a financial collapse but afterwards everything would return relatively easily to an earlier way of doing things (ye know, the way from just 4 years ago, and which is still 99% of how people do things :) )
There are loads of technologies that, despite being decades old, do not qualify. So, no, it’s not “primarily a function of time”. It absolutely is about the utility. We can only be in a position to judge utility when sufficient time has passed, and AI ain’t had enough time yet to prove its utility. Given enough time, it might prove as useful as electricity, or it might just sit alongside computer operating systems - never quite making it onto anyone’s “this changed the world” list, even if it has as much utility as an OS.