Was this the article you were referencing:
Classic Copenhagen: Hello Irma
I think it has less to do with the irma cartoon image and more to do with the Marimekko (マリメッコ) and Irma（イヤマ）store brands and products which are the type of cute European styled gifts and things that Japanese girls tend to go for.
The irma cartoon image does have that "maid" vibe going so I think that association is another cute factor for girls.
Here the Japanese portal for the store:
http://www.times-net.jp/SHOP/125661/list.html