He died because he wanted to. Let's just go by the facts in the anime/manga and not "what if's" please.
Also, some things to note:
Itachi once told Kisame that if they were to fight Jiraiya at that moment they met, they would both die. This is interesting because how could Jiraiya > Itachi & Kisame, but Six Paths Of Pain > Jiraiya .. when Itachi > fully resurrected 100% Nagato
Also Itachi defeated Orochimaru once when he was a part of Akatsuki and again when he came out of Sasuke. Jiraiya never managed to beat Oro and the 3rd Hokage had to give his life to even try to accomplish a win.
Food for thought yes?