A yard and a meter are close enough in my book to work as a fair measurement. My preference would be for meters though. I think it's a better fit to average size and reach of a normal humanoid.
However, measuring in multiples of 3, even with a metric system, can be difficult for those less math-inclined, especially if they're unfamiliar with the unit of measure being used.
5' measurements produce very nice metric-esque intervals(5, 10, 15, 20, etc..) and are rarely broken down into inches or smaller units of incremental measure, even if they are, it's usually feet, and 5' is a nice round 60" which works out well. I do feel it is a bit large for a normal humanoid, but from fingertip to fingertip it's not so bad.
In the end, my vote is: if it ain't broke don't fix it. And IMO this is one thing that just isn't broke.