brotkasten
Member
Have to question that character popularity drives anything in the plot.
Kakashi has been out of the spotlight for long stretches.
Jiraiya died.
Tons of popular minor characters do nothing for years.
Lets take a look at the last Naruto Character popularity poll, which was published in chapter 531, on March 9th, 2011 (this was when Shikamaru fought against Zombie-Akuma, just as a reference)
Naruto Uzumaki - 6,880 votes
Sasuke Uchiha - 5,791 votes
Kakashi Hatake - 4,828 votes
Gaara - 4,239 votes
Itachi Uchiha - 4,011 votes
Deidara - 3,623 votes
Minato Namikaze - 3,477 votes
Sasori - 3,152 votes
Shikamaru Nara - 2,533 votes
Hinata Hyūga - 2,517 votes
Iruka Umino - 2,494 votes
Sakura Haruno - 2,188 votes
Sai - 2,188 votes
Yamato - 1,925 votes
Neji Hyūga - 1,794 votes
Jiraiya - 1,723 votes
Hidan - 1,635 votes
Temari - 1,628 votes
Tobi - 1,621 votes
Rock Lee - 1,597 votes
Kushina Uzumaki - 1,338 votes
Kisame Hoshigaki - 1,320 votes
Pain - 1,320 votes
Konan - 1,320 votes
Killer B - 1,312 votes
Might Guy - 1,299 votes
Kankurō - 1,214 votes
Kiba Inuzuka - 1,079 votes
Ino Yamanaka - 989 votes
Shino Aburame - 989 votes
I know it's been over two years, but I think that Kakashi is still quite popular, which is why he didn't die during the pain invasion and won't die now.