"Yemen was supposed to be the success story for the White House," as the article notes. It was not. The War On Terror would better be called a War of Errors. As for some mistakes there is plenty of ground to speculate whether they were intentional or not.
The effort for regime change was meant to not involve sending in US troops and instead weapons, equipment and training. It is doubtful the public would have let another full scale invasion fly.
Everywhere we go to fight "terror" becomes a major migratory destination for radicalized Muslims, a lasting result of Cold War proxy war strategy. See the film "The Power of Nightmares" for a legit breakdown on the evolution via the tinkering of factions within the US government that got us to where we are now.