I think you missed the ending...
Walt was dying and he needed a way to get ALL the bad guys.
Just killing one or two of them would not have worked. He came up with a way to die on his terms and get all the bad guys at the same time.
I agree it was not the type of ending I was expecting, but I thought it was a well thought out twist.
Just finished reading your post... remember this is the movies, nothing real ever happens here. :teeth_smile: