I didn't mean to be unfair to the British. They knew how to run an empire but they didn't uplift nations in their spheres for the mutual profit of those peoples. They invested in those countries to profit the empire or make controlling the territory easier.
Sure, don't get me wrong, I didn't say they did. However, they were much better than most of the "competition".
No one ran a global empire better or more benevolently than the British until the Americans came along.
That is up for debate I think. :-) I even said as much during your past and current debacle in Iraq. "You even had the British with you, the best imperialists there have ever been, and you still couldn't take their advice and do the smart thing." (They moved to have Abu Ghraib bombed for example, it being such a powerful symbol for Saddam's oppressive rule. Did you? No instead you made it a symbol of your oppressive rule. It's such a rookie mistake it's painful to see.
And then sending his army complete with political leadership home? WTF? You didn't even do that to the Nazis until after several months. German army units and US units even patrolled together all through the summer of '45, to ensure a stable and peaceful transition. It wasn't until after that was secured that you started hunting Nazis in earnest. So analogously, following your own example, in Iraq you should have rounded up the republican guard in short order and left the rest to simmer until done. Then dealt with it. You didn't and ended up with Iraq a vassal state of Iran, and the bloody Isis in the north.
So, I understand that you try and sell the current US as the empire that thwarts all other empires, but from outside I (and many with me) just can't see it. We see business acumen, and nothing else. No knowledge of actual facts on the ground, no sense or knowledge of history (local or otherwise), no shrewdness, no long term plan or direction. And by your own explanation, that's perhaps not surprising as the US leadership almost guarantees that there can be none of the above. To be a skilled imperialist, you need knowledge, direction, and being in it for the long haul. The US system, with everybody changing all the time, as you point out guarantees that that won't happen.
And hence you get the many messes that you get yourself involved in. Half heartedly and haphazardly. You can't seem to neither shit, nor get off the pot. From Vietnam to Iraq the symptoms and outcome are the same. And everybody else knows this, beating the Americans is easy. Just bleed them until they lose interest, as they inevitably will. The US have no staying power. (Compare that with the British if you will.) Even two-bit Somali war lords understood this, and managed to pull it off without much effort.
Now, why the US as imperialists are a failure, is a good question, and one we could write books on (as others have), but let me end with saying that of course this isn't all bad, or even overwhelmingly so. I'd absolutely hate for the current US to start behaving like the British, even as late as the late nineteenth century, don't get me wrong. I'd rather see an inept US that doesn't really want to be imperialist, than one that would and started doing that competently. But I'd also rather see a US that took an even more complete step in that direction and avoided clumsiness like Iraq altogether.