[andre2907]

Even when Namie wasn't at her peak (1998-2004), she was still considered a HUGE name. I mean, if you look at magazine covers from that period, you'll see there was only two singers who often appeared in magazine covers: Ayu and Namie. Only the two of them, even though there was a huge gap between Ayu sales and Namie sales at that time. Namie was still a fashion leader and highly influential all those years and she never stopped being one of the most recognizable face in the Jpop industry even when she was being outsold by lots of other acts.

Today, in my opinion, a huge part of her popularity has to do with the fact she wasn't over-exposed in the last ten years. She had a big stable fanbase, was a recognizable face by almost everyone and worked steadily but she wasn't an omnipresent figure like many other acts (Ayu, for example). Besides, during those years she went through a lot of stuff that at the time really affected her image (pregnancy, shotgun wedding, divorce, family drama) but were vital to build the "strong woman" image she has now. She is really respected by women in Japan because of everything she's been through.

Also, the fact she was never overexposed helped her to attract back lots of fans who were with her during her peak. The nostalgia factor really helped her. Since she had such a huge impact on the 90s in Japan, her comeback means a lot to many people who were kids or teenagers during that era. It's usual for us to be attached to things we liked during our childhood or our teenager years and that really helped Namie's comeback.

Besides, Namie has always been a respected and well-liked figure by young woman in Japan. When the Vidal Sasoon commercials started airing, it reminded lots of women that besides a cute fashionable girl, Namie was still doing music.

Ayumi has always been an over-exposed figure, she never laid low so people could miss her (since her debut, she has always been Avex most important star and has been promoted such. Even now). Besides, she doesn't have such a "positive" image in Japan as Namie have (many people see her and her style as extremely annoying or are very sick of her). So I don't think she'll have a comeback like Namie is having now.