I think throwing arms are important, although not as important as range. I was curious because fans don't usually talk as much about outfielder arms today. When fans talk about players from the 60s, throwing arm seem to be the thing they talk about first. I don't know whether that was talked about more back then or whether it's just something that is more unforgettable when looking back.
Of course, defense in general was more important in past eras when there more balls in play. There was probably more variation between good and bad fielders back then too. Because there is so much hitting today, teams could afford to carry one or two defense only players. There were also no DH's then so there might have been more terrible defenders.