I'm 6' tall, and have a plus two ape index. I like running my bars at about 765. I decided on the width by doing pushups to failure with my hands at different widths, and it made me feel a lot stronger on the bike.
I think the wide bar craze probably originally came about from the watch-makers tool idea where big motions at the hands lead to smaller motions at the wheel which makes the steering less sensitive and more difficult to make mistakes. New, slack, long wheelbase bikes are already sooo stable, it seems like it's a lot less necessary, and slightly twitchier steering probably makes more techy climbing and descending easier.
Not to mention giving you a stronger position to resist g-outs, repeated chunky hits, more elbow articulation to bunny hop/pump/manual, etc. etc.
When I see short people on long bikes with wide bars it triggers my nerd. It's very difficult for me not to strike up a conversation and try to lead them around to bar width and then spray my opinions all over them. Similar to watching people work on jumps with their seats up. Or watching dads pump their kids tires up to 35 PSI at Duthie. Or anyone that has their brake lever mounts inside their shifter or dropper levers.