Why Did the US Test an Outdated Bomb in Mountains of Afghanistan?

The U.S. Military, apparently eager to test a huge out-dated bomb – anacronym “MOAB” for “Mother Of All Bombs” – dropped one for the first time in the sparsely populated mountains of Afghanistan this week.
The goal was apparently to fulfill Trump’s earlier campaign promise to ~”Bomb the hell out of ISIS.”

Unfortunately ISIS probably didn’t notice – or it’s members – spread out all over Asia, Africa, the Mid-East, Europe, and apparently the U.S. – were likely all shaking their heads and laughing.
Why? Because, if ISIS really exists as a coherent entity, clearly the MOAB is exactly the wrong way to deal with the MOADE (Mother Of All Decentralized Entities.)
Hopefully his advisers know this and  were just shining Mr. Trump on — or just curious to see what their outdated toy looked like in action.   Surely they know that sort of centralized destruction is nearly worthless — and certainly not cost effective – against decentralized 4th Generation Warfare.
On the bright side,  connected with the relatively benign and strangely ineffective Sarin-gas-excused attack on the Syrian air strip, perhaps this is Trump-The-Negotiator attempting to establish his POTUS credentials as willing killer with a minimum loss of life.
On the other hand, there’s a good chance it’s just one more example of abysmal government incompetence.
What do you think?