Garmins etc are all moving to optical wrist mounted HRMs, so why do dive computers still use those uncomfortable, Victorian era chest straps? It's really annoying being forced to put the strap underneath your wetsuit every time you want go diving
I don't think it's correct to call runners who don't acknowledge people "rude".
I don 't wave to runners, or acknowledge people I pass in the street who happen to be wearing the same brand of jeans as me, or rush to shake hands with people I see in the supermarket who have the same number of ears that I do.
It would be slightly precious at best (or more likely downright needy) in each of these three cases for the erstwhile counter party to consider themselves snubbed.