It takes an anime con to get Jpop guests to come to the US and most anime fans don't care about Jpop unless it's a theme for something on Cartoon Network or something from Final Fantasy. I'm guessing H!P's recent visits to Paris have had a bunch of people go to them. And plus its closer.
It's at least an 12 hour flight to France from Japan... I'd guess it's the same at least to the west part of America, so it's not really that much closer unless they're aiming for the middle or the east. ):
Chisato has said she's been on a diet, to lose 8kgs until their first day of tour. I'd say it shows. (: