Umm,I think he wants more people working for him......

He did kill the obvious seemingly outward trouble making guys and I am pretty sure that he did take their guns?

 

Why isn't that reasoning enough? It's his M.O. ....straight up. It's how he survives. He doesn't want to put forth any work himself and he loves power.....so he breaks people (killing Glenn and Abe) so they will do it for him.

He said it himself..... "I'm not going to grow a garden."

He didn't kill Glenn and Abe solely for revenge....that was part of it, but he didn't do it out of anger or rage because he lost some men. He did it to get them all to bend to his every wish.

 

Want to see Negan get angry? I bet he will really get his bowels in an uproar if he eats the hogs sent over by the Kingdom.

 

I think it's just that...he wants more people working for him....especially so to compensate for the many men he has lost.
I feel like Negan would get a bigger kick out of seeing fear in people's eyes, having power and authority over them and save the killings for the more poignant times to remind people of those things and make an example of people rather than killing all the time and killing willy nilly...

 

It's not like he seems to care much about his saviors anyway... If he gets to make one out of Daryl, why would he care if someone kills him later? He doesn't look like someone who'd lose sleep over Dwight's death either...