Why bother referencing neutral to ground in residential transformer?
I know you're looking for a &quot;tweet&quot; of an answer, a simplistic reason &quot;Oh, it's this&quot;. There's actually a lot to it.  It's not an ideology, it's hard empirical data culled from a sea of accident reports. They are using field data to &quot;min-max&quot; for minimum casualties.
What you're talking about is an isolated system.
That is a thing.  And yes, if properly maintained, it amounts to &quot;your first ground-fault is free&quot;.
I discuss the matter at length in this posting.
However, that &quot;first ground fault&quot; creates a treacherous situation for the rest of the system.
I had exactly that happen on a system I did not intend to be isolated.  I found it when working on a circuit that I had turned off, and I flashed hot to ground just to be sure of it, and I got a tiny blue arc, and the fluorescent lights on that circuit came back on.  The neutral was 120V from ground (whoopsie!) and the other phase was 240V from ground.  Neutral was now dangerous, even though I had turned off the breaker, and it was a darned good thing I had done the &quot;flash test&quot; and chased down the problem before proceeding, because I was about to handle neutral in a grounded metal box, and that would've kicked my butt.
So &quot;the first ground fault is free&quot; is only clever if you have maintenance people actively searching and testing for that first ground fault, and they repair it BEFORE a second ground-fault occurs.  Otherwise, it simply fails in silence, creating a time-bomb that is a worse situation than a grounded system, and bites you later with very unexpected behavior.
Indeed, Code does allow isolated systems on sites where on-site staff do active maintenance and monitoring of the system.  That's sure as heck not a house.