That's quite narrow, mine are 68cm, and I'm planning on swapping for some 72cm with a shorter stem, when I finish messing with the other bikes.
All the talk about how important bar width is on road bikes but somehow it doesn't apply to MTBs ...?
Ah, hang on - I found this video where the subject is discussed ...
My MTB is 15 years old and bars were generally not super-wide in those days. I am more interested in cross country and climbing rather than fast downhill MTB. I use a long stem, and the bars have zero rise. I always felt that my MTB bars were a bit wide and had been thinking of cutting them down by a couple of cms either side. I'll leave them alone! I certainly don't fancy even wider bars though.