I can't remember the last time I used vi and was unable to use arrow keys. That includes typical Linux installations (Vim, Busybox), Solaris (default is Vim, oddly, but I just confirmed arrow keys work in /usr/xpg4/bin/vi), and various BSDs (nvi).

I'm not a power vi user, though. I usually use JOE (thanks/blame to '90s Slackware education), but occasionally vi is more convenient. It wouldn't be nearly as convenient without the arrow keys as I never learned proper typing technique.