If you want to consider what's the most important skill for getting PP... it's speed.
Although, after much deliberation over the years, I feel that speed is probably the most important anyway, but that refers to speed as a whole... your finger speed, aim speed, reading speed. Aim becomes a problem when the speed is too fast... eg. tapping hand goes out of sync, can't reach notes, etc. So I'd say aim is a factor of speed, whereas precision would just refer to how accurately you can aim, which is not very important with big circles.
Accuracy might be very important, but to call it the most important skill, would be like saying "having 20/20 vision is the most important skill" - it's something that you need to have, but it's very hard to improve.
It's good to be able to play slow stuff and be accurate no matter what you play, but the fact is that lesser players can par with you on those maps, while not being able to match up at all on faster maps for a long time to come.