Why is the military oath so different between enlisted and officer?

I'll add that the view of the Founding Fathers was that the military leadership should not swear loyalty to any one individual in the government* (even the one who the sole authority to appoint them as a military officer rested with) and would instead swear to support the ideals of the Constitution.

This was reflected as the very first law passed by the newly formed Federal Congress after the Revolutionary War was for military officers and senior government officials to simly swear to "support the Constitution of the United States".
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* Of note, the British officers at that time swore an oath of loyalty to King George III specifically and the Founding Fathers found that to be abhorrent to the newly formed nation.

Sir, as a (former) career NCO, I would challenge your assertion.

As an enlisted NCO, I still issued orders. Those orders were still binding upon my Soldiers, and failure to obey them was still punishable under UCMJ.

And I was *absolutely* held accountable for those orders that I issued.

Now, I will say that as an enlisted Soldier, I had no UCMJ authority to enforce those orders, beyond that which was delegated to me by an Officer. But the assertion that only Officers are held responsible for orders they issue is a bit off base, IMHO.

As you put it, your orders were derived from the officer's (typically your commander's) orders and as a result, they are subject to the ultimate accountability. This isn't to say you could not be held accountable, but you are the delegated authority of that unit of which an officer bears the responsibility for. That said, a good officer confers with their NCOs to make sound orders, but ultimately they are the ones who should be making the decisions. I get that there are nuances in which you'll find NCOs making many of their own decisions for the enlisted under their charge, but ultimately that officer will be the first to answer to what went wrong (or right). Some even have good NCOs that manage to get things done in spite of the officer's ability, and some don't. But if you were to go rogue and issue orders that conflict with the officer's, and he/she consistently does nothing to correct this... sure you might be held accountable, but so will he or she. I have faced a couple of occasions where my NCOs have messed up going in the wrong direction (nothing major, just mistakes), and while I might have corrected their actions directly with them, they would rarely (if not never if I could help it) know what heat I took from the next step along the chain of command. Why? Because I claimed responsibility for my unit's actions vs pointing fingers at my NCOs. Regardless of whether I never ordered my NCOs to do it.

Maj Kevin "Mac" McLaughlin
Sure. But the same can be said of almost all Officers, as well. The PL is following Company Commander's orders, the Company Commander is following BN Commander orders and on and on up the chain. Likewise, the CO has to answer for PLs, the BC has to answer for COs and and and on up the chain.

And I did not say my orders were derived from higher, I said my authority to enforce them was delegated from higher. I issued plenty of orders that were self-contained and not based upon any orders I had received, unless you are counting the very broadest, most general "orders" like "take care of your troops."

This was true in pretty much all of my NCO positions, and it was especially true when I was a PSG with no PL or when I was a PSG with a particularly incompetent PL. But it was also true when I was slotted in a MAJ position and when I was slotted in a CPT position.

Just because I was enlisted did not mean I had no authority to issue orders in my own right.