Why is the most powerful military on earth still fighting ground wars?

Because it still requires boots on the ground to control a population while also providing security for real change to start and take place. That and the use of terrorism and guerrilla warfare means that those you are fighting just blend back in with the civilian population and much or what you are fighting are civilians to begin with. There are no large, standing armies that we are currently fighting with defined battle lines but instead civilian political, religious and civilian terrorist groups who will use anything and any tactic they can to win and establish their own objectives and agenda while embedding themselves among and within the civilian population.

Simply killing the enemy is hardly ever the goal of any military campaign. The goal is to force the other side to do whatever it is that you want them to do...it could be that you want them to leave a certain area (Kuwait, Gulf War 1), or to get them to agree to stop attacking your shipping and enslaving your sailors (Barbary Wars). Killing some of them (or a lot of them) is simply a method to reach the goal that is used after other methods (politics) have failed.

No idea!!!???!!!

Because using a nuclear weapon to get the guys behind that wall is impractical.

Okay................Patton- Just how do you expect to take and hold ground without people getting muddy and sweaty?

Other than nuking Japan, air power has never delivered victory by itself. Never.

You never actually hold territory until there are boots on the ground.

Do some basic research on military tactics and strategy before posting a "question" that makes you look really foolish.