Have lived in both New Zealand and US and made regular use of water kettles. I'm not sure if popularity is a function performance (or if there are other cultural reasons) but I can confirm that water kettles connected to 240V are way more awesome... P=IV and all.
This extends to home espresso makers. Some international models of home espresso makers get rave reviews in AU/NZ, but lackluster reviews in the US. Only so many watts you can get on 120V before you exceed amperage constraints.