I'm 6'1" and went from a 90's bike with narrow bars that I'd cut down to a 29er this year, getting back into biking.

One of the first things I did was cut the 700 bars down to 670, they still feel on the wide side of comfortable, but at least they are now in the comfortable "range" for me.

I also, against the LBS's advice went from a 65mm steam to 120, felt better to ride to me. One ride with a group that pushed my downhill gnarly limits, and well, I have a 60mm steam now!
Back to the shorter steam makes the bars feel less wide (for me anyway).

I guess the thing is: You have to set up your bike for how you like it, how you ride it and where you ride it.

There is no one right answer.

I would like to take another 10mm of each end of the bars, but given how I stuffed up steam length, I'll leave it a while then maybe chop some off.