I used to feel that way once, but then some fucked up Ayu stans showed me the dark side of Ayu fandom so I haven't really been a huge fan anymore. I do still listen to her music but not as much as I used to back in 2006-2007.
keep in mind the tactics used to make albums like that sell, though. every AKB48 album has three versions released (Tsugi no Ashiato had four), so collectors have to buy multiple copies to get all of the content. it's even more noticeable with singles, since groups like AKB48, Morning Musume, etc., often have upward of 6 versions of the single available, which forces fans to get multiple copies to get the songs they want. industry sales at large have noticeably declined, though, even if a few individual acts can still break a million, there is no debate about that.
"CD sales in Japan are declining. They went from ¥310 billion in 2012 to ¥254 billion in 2014." "CD buyers tend to be in their 30s or older (“Best of” albums do well here)." http://www.japantimes.co.jp/culture/2015/12/27/music/future-japanese-music-depend-streaming-services/ "Japan has the highest median age in the world. Even in much younger America, it’s the older folks who buy most of the CDs." "Meanwhile, the practice of renting CDs is still quite popular in Japan, as copyright law there makes such an industry legal there, unlike in the U.S. This makes it quite easy for listeners to rent an album at 10% of the price of buying it and just rip it to their computer." http://fortune.com/2014/09/18/japan-cd-sales/ No all-time top 10 record has come out since 2002; Ayu's last record to reach one million sales was in 2006 (that's right, NEXT LEVEL sold less than one million): https://en.wikipedia.org/wiki/List_of_best-selling_albums_in_Japan
"Though I don't really see artists today selling millions since it's the age of Spotify and Youtube". Actually, that doesn't apply to Japan, where people still buy a lot of CDs and DVDs, that's why sales are relevant...
Is the new album really that good? I've but jaded with her new stuff for a while but listening to her old stuff again recently is probably the kick up the ass I need to sit down and listen properly. This is serious shit.