Reborn ran for eight years and it's merchandise sold as crazy throughout (and even after) that period. I think Reborn deserves a celebration this year.
Death Note started in '03, so if there's a celebration for it, they are late. If that's the case, we could still expect a Reborn celebration later this year, probably.
Reborn was just another action manga. Death Note was a pop culture phenomenon similar to how Shingeki is right now. It was something bigger than manga, a major crossover success. At it's height, Reborn had some crossover appeal to fujoshi, but was mostly something with little reach beyond core action manga fans. It's sales were solid, but not "crazy". If it were serialzied today Reborn would sell less than Assassination Classroom and Kuroko. The anime was not well received. Reborn was not that heavily merchandised, by Japanese standards. Reborn was never as heavily promoted as Gintama. It was never even close to true merchandising behemoths like Tohou Project, KanColle, Kagepro, or The Idolm@ster. I doubt Jump does anything for Reborn's tenth, or D. Gray Man's, for that matter. Neither even run in the magazine anymore. Reborn was never even close to comparable to Death Note or Gintama, both of which are getting recognition for their tenth anniversaries. Gintama is on the spine this year, just like they did for Naruto, Bleach, and One Piece.
Death Note started in issue #1, 2004. Issue one is almost always released in December, with a copyright for the following year. Death Note is copyrighted for 2004. Manga are generally copyrighted for when the first volume comes out, not the first chapter. Death Note started about three weeks before new years.