Brother, if you google Olive, Figs and Honey on google; you will find numerous articles on their benefits and zikr in Quran. I dunno how feel about that, either they r so beneficial because their zikr is found in Quran or Quran chose them because of their benefits.
Either way you take it; conclusion would be Everything you find in Quran has its importance and value.
ALLAH says in Quran
I am not here to convince you to Celebrate or mourn these anniversaries; but dont call them unimportant near ALLAH. Certainly they are of great importance thats why ALLAH is Specifically picking these days to send Salam on Prophet a.s, and on the other occasion you see a prophet a.s doing that for himself.
Not only you find zikr of these days in Quran but these are the days ALLAH chooses to send salam on his Prophet a.s
Wasalam.